Articles de revues : « Dilatometri »

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Pawłowski, B., P. Bała et R. Dziurka. « Improper Interpretation of Dilatometric Data for Cooling Transformation in Steels ». Archives of Metallurgy and Materials 59, n^o 3 (28 octobre 2014) : 1159–61. http://dx.doi.org/10.2478/amm-2014-0202.

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Abstract Dilatometry is the most commonly method of producing CCT diagrams and analyzing phase transformations during cooling (as well as transformations during heating) and it permits the real-time monitoring of the extent of reaction in terms of dimensional changes due to phase transformation. All modern dilatometers are fitted with computerised systems which collect dimensional change signals versus temperature to plot a dilatometric curve and also to calculate and plot the derivative of the relative dimensional change with respect to temperature. Unfortunately, elaborated by dilatometers manufacturers software, in many cases could lead to wrong interpretation of phase transformations during cooling.

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Zachreini, Indra, Mulyati Sri Rahayu, Harvina Sawitri et Fachraniah Fachraniah. « UJI BANDING EFEKTIVITAS H2O2 3%, DAN LARUTAN CAMPURAN H2O2 3% DAN MADU 1:1 SEBAGAI SERUMINOLITIK SECARA DILATOMETRI ». AVERROUS : Jurnal Kedokteran dan Kesehatan Malikussaleh 2, n^o 2 (16 février 2018) : 82. http://dx.doi.org/10.29103/averrous.v2i2.427.

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Serumen adalah campuran material sebasea dan sekresi apokrin dari kelenjar seruminosa yang bersatu dengan epitel deskuamasi dan rambut.Menurut data World Health Organizationtahun 2007, insidensi serumen obsturan di Indonesia sebesar 13% dan menempati urutan kedua terbanyak di Asia Tenggara.Serumen obsturan tipe kering dan keras, memerlukan seruminolitik sebelum dilakukan tindakan ekstraksi.Terdapat 2 jenis serumenolitik yaitu solutio aqueos dan solutio organic. Penelitian ini bersifat eksperimental dengan mengukur kerapatan massaserumen menggunakan metode dilatometri pada serumen yang dilarutkan dengan H2O2 3%, dan larutan campuran H2O2 3% dan madu perbandingan 1:1. Dilakukan analisa kerapatan massa serumen berdasarkan perbandingan massa serumen per volume serumen dalam masing-masing larutan. Hasil penelitian diperoleh, larutan campuran H2O2 3% dan madu dengan perbandingan 1:1mempunyai kerapatan massa serumen lebih rendah dibanding larutan H2O2 3% sebagai serumenolitik , namun secara statistik tidak terdapat perbedaan bermakna kerapatan massa serumen antara larutan H2O2 3% dengan larutan campuran H2O2 3% dan madu perbandingan 1:1.

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Břuska, M., J. Beňo, M. Cagala et V. Jasinková. « Dilatometric Characterization of Foundry Sands ». Archives of Foundry Engineering 12, n^o 2 (1 avril 2012) : 9–14. http://dx.doi.org/10.2478/v10266-012-0027-8.

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Dilatometric Characterization of Foundry Sands The goal of this contribution is summary of physical - chemistry properties of usually used foundry silica and no - silica sands in Czech foundries. With the help of dilatometry analysis theoretical assumptions of influence of grain shape and size on dilatation value of sands were confirmed. Determined was the possibility of dilatometry analysis employment for preparing special (hybrid) sands with lower and/or more linear character of dilatation.

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Lebedeva, N. V., Yu M. Markova, A. I. Ziza et D. M. Anisimov. « STUDY OF THE MICROSTRUCTURE OF MARTENSITE-BAINITE STEELS AND NICKEL ALLOYS WHEN MODELING HEAT TREATMENT MODES USING A DILATOMETRIC METHOD ». Industrial laboratory. Diagnostics of materials 85, n^o 6 (10 juillet 2019) : 30–36. http://dx.doi.org/10.26896/1028-6861-2019-85-6-30-36.

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We present the results obtained using the equipment available at the Center for collective use “Composition, structure, properties of structural and functional alloys” NRC “Kurchatov Institute” — CRISM “Prometey”: DIL 805A/D (TA Instruments) and DIL 402C (Netzsch) dilatometers. Dilatometric analysis which provides determination of the temperature coefficient of linear expansion and the temperature of phase transitions, as well as evaluation of the transformation kinetics, can also allow simulation of heat treatment modes to identify the size of the former austenitic grain using vacuum etching and conduct the research aimed at improving the technology of thermal and thermomechanical processing (TMO) of steels and alloys. The experiments were carried out both in vacuum and in dynamic helium atmosphere. The main methodological difficulties that we have faced with are described. For steels of martensite and martensite-bainite class (38KhMA, 38KhN3MFA, 20Kh3NMFA) conditions of vacuum etching in the chamber of the dilatometer are specified. The efficiency of the method for martensite-bainite steels in determination of the grain size compared to traditional methods of etching is deminstrated. The effect of thermodeformation parameters on the size of austenitic grain is estimated. When modeling the heat treatment modes by the dilatometric method, the microstructure of KhN55MVTs nickel alloy was also analyzed. Changes in the size and morphology of the grain structure at different stages of heat treatment are revealed. The obtained results were used to adjust the current modes of heat treatment and obtain a uniform fine-grained structure. The combined application of dilatometric and metallographic analyzes after vacuum etching of the material decreases the production costs attributed to obtaining the desired microstructure upon thermal and thermomechanical processing of the products and blanks.

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Chen, Peng, Yun Bo Xu, Xiao Long Yang, Hong Liang Yi et Guo Dong Wang. « Isothermal Bainite Transformation in Aluminium Bearing TRIP Steel ». Materials Science Forum 749 (mars 2013) : 237–42. http://dx.doi.org/10.4028/www.scientific.net/msf.749.237.

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In this work, the bainite transformation during isothermality of aluminium bearing TRIP steel was studied by dilatometric experiment on a pushrod Formastor-F highspeed dilatometer with radio frequency induction heating. The aluminium bearing TRIP steel consisted of the microstructure of austenite, ferrite and bainite in the form of laths which produced by intercritical annealing and isothermal transformation followed by rapid cooling. The effect of intercritical annealing temperature and isothermal transformation temperature were studied by dilatometric experiment and JEOL JXA-8530F Electron Probe Microscopic Analyzer (EPMA).

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Neumeier, J. J., et Genevieve A. Nelson. « Sapphire dilatometer cell for measuring the thermal expansion of solids ». Review of Scientific Instruments 93, n^o 6 (1 juin 2022) : 063903. http://dx.doi.org/10.1063/5.0091377.

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Capacitive-based dilatometry is used to determine the thermal expansion of solid specimens over a broad temperature range and for the study of structural and thermodynamic phase transitions. It can detect length changes of 0.1 Å or better. Dilatometer cells have been constructed of metals, such as copper or silver, and non-metals, such as silicon and fused silica. Sapphire is a good candidate for the construction of a dilatometer cell. It has excellent thermal conductivity, a well-behaved thermal expansion of moderate magnitude, especially below ∼60 K, and is readily available. The design, fabrication, and testing of a sapphire dilatometer cell are described herein.

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Matjeke, Velaphi Jeffrey, Josias Willem van der Merwe et Nontuthuzelo Lindokuhle Vithi. « Determination of Critical Transformation Temperatures for the Optimisation of Spring Steel Heat Treatment Processes ». Metals 11, n^o 7 (24 juin 2021) : 1014. http://dx.doi.org/10.3390/met11071014.

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Bogie spring performance can be improved by using the exact heat treatment process parameters. The purpose of the study is to determine the critical transformation temperatures and investigate the effect of the cooling rates on microstructural and mechanical properties. The precise determination of the required cooling rates for the particular grade of steel is important in order to optimise the heat treatment process of heavy-duty compression helical spring manufacturing. A traditional heat treatment system for the manufacture of hot coiled springs requires heating the steel to homogenize austenite; then, it is decomposed to martensite by rapid cooling. By analyzing the transition properties by heating and differing cooling rates, this analysis examines the thermal behaviour of high strength spring steel. Using the dilatometer and differential scanning calorimeter, scanning electron microscope, optical microscope, and hardness checking, critical transition temperatures and cooling rates of three springs steels were measured. Although the thermal transformation of materials has been researched for decades using dilatometers, not all materials have been characterized. The research offers insights into the critical transformation temperatures for the defined grades of spring steel and the role of cooling rates in the material’s properties. Mechanical properties are influenced by the transition data obtained from the dilatometric analysis.

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Drozd, Zdeněk, Zuzanka Trojanová et Pavel Lukáč. « Experimental Study on the Relation between Elastic and Thermal Deformation of the AZ31 Magnesium Alloy and Composite ». Key Engineering Materials 465 (janvier 2011) : 423–26. http://dx.doi.org/10.4028/www.scientific.net/kem.465.423.

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The dilatation characteristics of the continuosly cast AZ31 alloy and composite with AZ31 matrix reinforced by SiC nanoparticles were investigated in the temperature range of 20-410 °C. The axis of specimens was either parallel or perpendicular to the casting texture. The linear thermal expansion of the alloy as well as the composite was measured in an argon protective atmosphere using a Netzsch 410 dilatometer. The relative elongation and coefficient of thermal expansion are the main experimental results obtained using dilatometry. The temperature dependence of the elastic modulus can be calculated using analysis of the dilatometry results.

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Maca, K., V. Pouchly et A. R. Boccaccini. « Sintering densification curve : A practical approach for its construction from dilatometric shrinkage data ». Science of Sintering 40, n^o 2 (2008) : 117–22. http://dx.doi.org/10.2298/sos0802117m.

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This article summarizes the usage of high-temperature dilatometry in ceramic processing and powder technology with special attention on the description of the sintering process. A practical method for transformation of dilatometric shrinkage data into densification curves (the dependence of the sample density on sintering temperature or time) is described in detail. A new automatic procedure to recalculate sintering shrinkage data allowing the plot of the densification curve has been developed, which is presented here.

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Kövér, Michal, et Peter Sláma. « Aluminium Alloys Measurement in Quenching Dilatometer and Application of the Data ». Advanced Materials Research 1127 (octobre 2015) : 73–77. http://dx.doi.org/10.4028/www.scientific.net/amr.1127.73.

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Thermal expansion is an important material property. From change of this quantity phase transformations can be evaluated. Therefore dilatometry is a common tool for construction of transformation diagrams in steel and prediction of material structure according to the performed heat treatment. However there are some restrictions for quenching dilatometers, such as magnetic properties of the material or weldability of the controlling and measuring thermocouple. In this article the quenching dilatometry is proposed for evaluation of precipitation during continuous cooling from solution annealing temperature. Aluminium alloy EN AW 6082 was chosen as the experimental material. Due to poor weldability of the experimental material new sample geometry was introduced.

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Romanov, G. N., P. P. Tarasov, P. K. D’yachkovskiy, A. P. Savitskii et L. S. Martsunova. « Liquid-phase sintering of Al with addition of Ti ». Science of Sintering 38, n^o 1 (2006) : 55–62. http://dx.doi.org/10.2298/sos0601055r.

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Samples made from aluminium-titanium elemental powder blend with titanium contents ranging from 5 to 20 at. % were prepared by die pressing and subsequent sintering under vacuum in a dilatometer quartz tube at 700, 800 and 900 ?C. Dilatometric and heating curves of sintering were analysed and discussed in connection with X-ray data and results from microstructural investigations. .

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Rajak, Neeraj K., Neha Kondedan, Husna Jan, Muhammed Dilshah U, S. D. Navya, Aswathy Kaipamangalath, Manoj Ramavarma, Chandrahas Bansal et Deepshikha Jaiswal-Nagar. « Setup of high resolution thermal expansion measurements in closed cycle cryostats using capacitive dilatometers ». Journal of Physics Communications 5, n^o 12 (1 décembre 2021) : 125004. http://dx.doi.org/10.1088/2399-6528/ac3a44.

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Abstract We present high resolution thermal expansion measurement data obtained with high relative sensitivity of ΔL/L = 10−9 and accuracy of ± 2 % using closed cycle refrigerators employing two different dilatometers. Experimental details of the set-up utilizing the multi-function probe integrated with the cold head of two kinds of closed cycle refrigerators, namely, pulse tube and Gifford-McMahon cryocoolers, has been described in detail. The design consists of decoupling the bottom sample puck and taking connections from the top of the multi-function probe to mitigate the vibrational noise arising from the cold heads, using which smooth and high quality thermal expansion data could be obtained. It was found that dilatometer#2 performs a better noise mitigation than dilatometer#1 due to the constrained movement of the spring in dilatometer#2. This was confirmed by finite element method simulations that were performed for understanding the spring movement in each dilatometer using which the effect of different forces/pressures and vibrations on the displacement of the spring was studied. Linear thermal expansion coefficient α obtained using both dilatometers was evaluated using derivative of a polynomial fit. The resultant α obtained using dilatometer#2 and either of the closed cycle cryostats on standard metals silver and aluminium showed excellent match with published values obtained using wet cryostats. Finally, thermal expansion measurements is reported on single crystals of two high temperature superconductors YBa2Cu3−x Al x O6+δ and Bi2Sr2CaCu2O8+x along the c-axis with very good match found with published data obtained earlier using wet liquid helium based cryostats.

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Mohapatra, Goutam, et Satyam S. Sahay. « A Probabilistic Approach to Analyze Austenite to Ferrite Transformation in Fe-Ni System ». Defect and Diffusion Forum 279 (août 2008) : 71–77. http://dx.doi.org/10.4028/www.scientific.net/ddf.279.71.

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Dilatometer is often used for in situ measurement of phase transformation by monitoring the length change during heating or cooling cycle. However, the inevitable temperature gradient across the specimen length during inductive heating, introduces uncertainty in temperature measurements and hence the associated phase transformation kinetics. Due to this uncertainty, it is more meaningful to interpret the transformation kinetics from dilatometry in terms transformation ranges instead of unique values of fraction transformed. In the present work, a probabilistic approach has been used to predict the fraction transformed ranges, arising due to the temperature gradient during dilatometry. The approach has been validated for Fe-5.93 at.% Ni undergoing austenite to ferrite phase transformation at various constant cooling rates.

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HADJADJ, L., R. AMIRA et M. BOUCHEAR. « COMPARATIVE STUDY OF THE PHENOMENA OF PRECIPITATION IN Al–Zn–Mg ALLOY BY THE DIFFERENTIAL SCANNING CALORIMETRIC AND THE DILATOMETRY AND INTERPRETATION OF DILATOMETRIC EFFECTS ». International Journal of Modern Physics B 26, n^o 19 (16 juillet 2012) : 1250076. http://dx.doi.org/10.1142/s0217979212500762.

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Our aim is to contribute to comprehension of the phenomena of precipitation in the Al–Zn–Mg alloys. For this, we have made a comparative study of the transformations of phases using the differential scanning calorimetric and the dilatometry. This last technique is relatively new in the case of Al–Zn–Mg alloys. It consists of two opposite effects (contraction and expansion) observed on the dilatometric curves. These effects translate two opposite metallurgical phenomena which are generally the precipitation and the dissolution.

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Kim, Se Jong, Yi Gil Cho, Dong Woo Suh, Sung Joon Kim, Gyo Sung Kim et Heung Nam Han. « Boundary Migration Induced Plasticity during Recrystallization and Growth under Applied Stress ». Materials Science Forum 558-559 (octobre 2007) : 533–37. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.533.

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In general, plastic strain occurs over a certain stress, called yield stress. However, it has been reported that the permanent strain could happen during boundary migrating even under the extremely slight externally applied stress. In this study, we performed dilatometry experiments under the various compressive stresses and measured the amount of recrystallization and growth induced permanent strain. A new empirical constitutive equation was suggested to describe the recrystallization and growth induced plasticity. This equation was verified by comparing the calculated values with dilatometric experimental data under the various compressive stresses.

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Altamirano-Guerrero, Gerardo, Emmanuel J. Gutiérrez-Castañeda, Omar García-Rincón et Armando Salinas-Rodríguez. « Experimental Determination of Continuous Cooling Transformation Diagrams of Hot-Rolled Heat Treatable Steel Plates Using Quenching Dilatometry ». MRS Proceedings 1812 (2016) : 129–34. http://dx.doi.org/10.1557/opl.2016.29.

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ABSTRACTThis article outlines the use of quenching dilatometry in phase transformation kinetics research in steels under continuous cooling conditions. For this purpose, the phase transformation behavior of a hot-rolled heat treatable steel was investigated over the cooling rate range of 0.1 to 200 °C/s. The start and finish points of the austenite transformation were identified from the dilatometric curves and then the continuous cooling transformation (CCT) diagrams were constructed. The experimental CCT diagrams were verified by microstructural characterization using scanning electron microscopy (SEM) and Vickers micro-hardness. In general, results revealed that the quenching dilatometry technique is a powerful tool for the characterization and study of solid-solid phase transformations in steels. For cooling rates between 200 and 25 °C/s the final microstructure consists on plate-like martensite with the highest hardness values. By contrast, a mixture of phases of ferrite, bainite and pearlite predominated for slower cooling rates (10-0.1 °C/s).

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Milkereit, Benjamin, Michael Reich et Olaf Kessler. « Detection of Quench Induced Precipitation in Al Alloys by Dilatometry ». Materials Science Forum 877 (novembre 2016) : 147–52. http://dx.doi.org/10.4028/www.scientific.net/msf.877.147.

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Quenching is a critical step during the strengthening age hardening of Aluminium alloys. To obtain optimal technological results, parts should be quenched with the upper critical cooling rate. The precipitation behaviour of Al alloys during cooling from solution annealing and thereby the critical cooling rates are typically investigated by in-situ measurements with differential scanning calorimetry (DSC). Conventional DSCs are limited at cooling rates below 10 Ks-1. Unfortunately, medium to high strength Al alloys typically have critical cooling rates between 10 and some 100 Ks-1. Recently it was shown that dilatometry is generally able for in-situ detection of precipitation in Al alloys. Dilatometry allows controlled cooling up to some 100 Ks-1 and therefore covers the cooling rate range relevant. In this work, we aim to show up and discuss possibilities and limitations of dilatometric detection of quench induced precipitates in 2xxx, and 7xxx Al alloys. The basic method will be presented and results will be compared with DSC work.

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Liu, Yuan, Yan Han, Sheng Yin et Fei Zhao. « Metastable Austenite Transformation Kinetics of Medium-Carbon Silicon-Rich Steel during Partitioning in a Q & ; P Process ». Metals 10, n^o 6 (2 juin 2020) : 738. http://dx.doi.org/10.3390/met10060738.

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In the present study, quenching and partitioning (Q & P) treatment of a medium-carbon silicon-rich steel was processed by a dilatometer. The volume fraction of the retained austenite at different partitioning times was determined by X-ray diffraction (XRD). The metastable austenite transformation process after different partitioning times was studied by a combination of dilatometry, XRD, and transmission electron microscopy (TEM). Analysis of the transformation kinetics of metastable austenite during partitioning by means of dilatometry and the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation was carried out. The results show that the volume fraction of retained austenite increases first and then decreases with the increase of the partitioning time. The transformation active energy Q = 141 kJ·mol−1 and the Avrami exponent n = 1. The transformation product of metastable austenite is needle-like bainite, which grows perpendicularly towards the boundary of the austenite. Finally, the blocky austenite was divided into lath-shaped forms.

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Soliman, Mohamed, Mehdi Asadi et Heinz Palkowski. « Role of Dilatometer in Designing New Bainitic Steels ». Advanced Materials Research 89-91 (janvier 2010) : 35–40. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.35.

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Dilatometric measurements were used to design the processing parameters of two types of bainitic steels. The first type is a hypoeutectoid ultra fine bainite steel, for which the dilatometer was used to locate the temperature at which cementite is completely dissolved during intercritical annealing (TC). The intercritical annealing temperatures are then selected will above TC. To obtain the martensite start temperatures (MS), the steel is quenched to the room temperature (RT) from these selected temperatures and then the bainite transformation temperatures were selected to be well above MS. The dilatometer was then used to monitor the bainite transformation kinetics from which the required time frames for cessation of the bainitic reactions were estimated. In the second type, bimodal bainite had been produced in thermo-mechanically processed TRIP-steel. A deformation dilatometer is used to perform three deformation-steps before slow cooling to form approx. 30% polygonal ferrite. The material was then rapidly cooled to the first bainite formation temperature. During this step, the dilatometer was used to monitor the bainite reaction from which the required time for 50% decomposition of austenite is estimated. The martensite start of the undecomposed austenite was located by quenching to RT. The second bainite transformation step was then performed well above the new MSII to form a second generation of finer bainite.

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Soliman, Mohamed, Heinz Palkowski et Adel Nofal. « Thermo-Mechanically Processed Multi-Phase Ductile Iron : Microstructure Development ». Key Engineering Materials 457 (décembre 2010) : 199–204. http://dx.doi.org/10.4028/www.scientific.net/kem.457.199.

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Using thermo-mechanical simulator equipped with dilatometry system, two ductile iron alloys with different Mn-content are processed by combining both, well defined deformation process and subsequent controlled cooling in a single processing chain to control the final microstructure. Accordingly, ductile irons with four different structrues are produced namely, martensite, ausferrite, martensite+ferrite and ausferrite+ferrite. Depending on the dilatometric measurments, the ferrite formation temperature-range has been defined for both alloys. Preferential transformation of austenite to ferrite at graphite nodules during cooling is observed. It is also observed that the formation of ferrite during cooling results in both decreased martensite start of the undecomposed austenite and accelerated kinetics of ausferrite formation.

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Kim, Jae Hong, Dae Cheol Ko et Byung Min Kim. « Hardness Prediction of Tailor Rolled Blank in Hot Press Forming Using Quench Factor Analysis ». Key Engineering Materials 729 (février 2017) : 110–14. http://dx.doi.org/10.4028/www.scientific.net/kem.729.110.

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This paper aims to predict the hardness of hot formed part for tailor rolled blank (TRB) by the FE-simulation coupled with quenching factor analysis (QFA). Dilatometry test of boron steel is performed at various range of cooling rates from 0.2 to 100°C/s using the dilatometer with forced air cooling system. The dilatometry test provides a hardness data according to cooling curves which are used to determine the material constants (K1~K5) of QFA and the time‒temperature‒property (TTP) diagram of boron steel. Then, FE‒simulation of hot press forming is conducted to predict the cooling curves of hot formed TRB part with a thickness combination of thicker 1.6mm and thinner 1.2mm which is called as rear side member of automotive component. The cooling curves of FE-simulation are applied to predict the hardness of hot formed rear side member using the QFA. Also, experiment of hot press forming is performed to verify the predicted results and to examine the effect of cooling curves on the hardness.

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Wang, Xiao Hui, Xiao Lin Liu et Jian Feng Chen. « Sintering Behavior and Mechanism of Pure BaTiO₃ Ceramic Prepared by High-Gravity Reactive Precipitation ». Advanced Materials Research 11-12 (février 2006) : 27–30. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.27.

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Sintering behavior and mechanism of barium titanate powders prepared by high-gravity reactive precipitation (HGRP) process has been investigated by a dilatometer. The mean particle size of barium titanate powders prepared by HGRP was about 80 nm. Pure BaTiO3 pellets were sintered at a constant heating rate of 2.0 K/min and the temperature of shrinkage-onset for pellet was 1060°C. The maximal shrinkage was 165um and the maximum of shrinkage rate was 8.0 x 10-3 / min at 1170°C. The sintering mechanism for the initial stages of sintering was determined by isothermal dilatometric measurements and was found to be viscous flow.

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Hunkel, Martin, Juan Dong, Jeremy Epp, Daniel Kaiser, Stefan Dietrich, Volker Schulze, Ali Rajaei, Bengt Hallstedt et Christoph Broeckmann. « Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry ». Materials 13, n^o 22 (10 novembre 2020) : 5058. http://dx.doi.org/10.3390/ma13225058.

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Martensitic steels are tempered to increase the toughness of the metastable martensite, which is brittle in the as-quenched state, and to achieve a more stable microstructure. During the tempering of steels, several particular overlapping effects can arise. Classical dilatometric investigations can only detect effects by monitoring the integral length change of the sample. Additional in-situ diffractometry allowed a differentiation of the individual effects such as transformation of retained austenite and formation of cementite during tempering. Additionally, the lattice parameters of martensite and therefrom the tetragonality was analyzed. Two low-alloy steels with carbon contents of 0.4 and 1.0 wt.% and a high-alloy 5Cr-1Mo-steel with 0.4 wt.% carbon were investigated by dilatometry and in-situ diffractometry. In this paper, microstructural effects during tempering of the investigated steels are discussed by a comparative study of dilatometric and diffractometric experiments. The influence of the chemical composition on the tempering behavior is illustrated by comparing the determined effects of the three steels. The kinetics of tempering is similar for the low-alloy steels and shifted to much higher temperatures for the high-alloy steel. During tempering, the tetragonality of martensite in the steel with 1.0 wt% carbon shifts towards a low carbon behavior, as in the steels with 0.4 wt.% carbon.

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Wang, Changliang, Feng Li, Can Ding, Hui Chang et Lian Zhou. « Investigation of phase transformation in Fe microalloyed Ti6Al4V alloy during continuous heating process ». MATEC Web of Conferences 321 (2020) : 12010. http://dx.doi.org/10.1051/matecconf/202032112010.

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The phase transformation and dilatometric curves in Fe microalloyed Ti6Al4V alloy (Ti6Al4V-Fe) during continuous heating at 1 ℃ /min heating rate had been studied by dilatometer and metallographic methods, and β phase transition temperatures of alloy were obtained. In order to validate the accuracy of these β phase transition temperature and microstructure evolution, the relative phase concentration and the evolution of microstructure which were acquired by cooling after tempering were analyzed by metallographic microscope. The results illuminated that the expansion method was able to accurately measure the β transformation temperature of Ti6Al4V-Fe alloy. The lathy-shaped α phase decreased significantly disappeared in the range of 838℃ to 988℃, and the α→β phase transformation occurred.

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Talebi, Seyyed, Mohammad Jahazi et Haikouhi Melkonyan. « Retained Austenite Decomposition and Carbide Precipitation during Isothermal Tempering of a Medium-Carbon Low-Alloy Bainitic Steel ». Materials 11, n^o 8 (15 août 2018) : 1441. http://dx.doi.org/10.3390/ma11081441.

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The effect of isothermal tempering on retained austenite decomposition and carbide precipitation were investigated in a medium-carbon low-alloy bainitic steel. High-resolution dilatometry was used to perform isothermal tempering at 350 °C, 550 °C and 600 °C for different holding times up to 16 h. The decomposition of retained austenite, morphology and composition of carbides were investigated by analyzing the dilatometric curves and were confirmed through scanning and transmission electron microscopy observations. The decomposition behavior of retained austenite varied significantly as a function of the tempering temperature with a full decomposition observed at 600 °C. It was also found that by increasing the tempering temperature from 550 °C to 600 °C, carbides precipitate approximately twice as fast, and evolve from M3C type to Cr7C3 and Cr23C6 after 16 h of tempering at 600 °C.

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Pieczonka, Tadeusz, et Jan Kazior. « Microstructure Evolution during Sintering of Aluminium in Nitrogen ». Advanced Materials Research 811 (septembre 2013) : 64–71. http://dx.doi.org/10.4028/www.scientific.net/amr.811.64.

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High purity aluminium powder was sintered in a dilatometer in flowing high purity nitrogen. The distinct shrinkage segments observed on the dilatometry curves were the basis of experiments consisting of interrupted sintering. In this way compacts with microstructure frozen at different steps of sintering cycle were produced. Optical microstructure examinations and LECO analysis of nitrogen content showed the development of aluminium nitriding. Additionally, X-ray diffraction was used to examine phases appearing in the system investigated. Microstructure analysis of structural components revealed evidence that isothermal sintering proceeds in the presence of a liquid phase, despite taking place below the melting point of aluminium. It seems that aluminium nitrogen interactions are responsible for the appearance of this phase, which is accompanied by extensive shrinkage.

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Pieczonka, T., M. Sułowski et A. Ciaś. « Atmosphere Effect on Sintering Behaviour of Astaloy CrM and Astaloy CrL Höganäs Powders with Manganese and Carbon Additions / Wpływ Atmosfery Na Spiekalność Komercyjnych Proszków Höganäs Astaloy CrM I Astaloy CrL Z Dodatkami Manganu I Węgla ». Archives of Metallurgy and Materials 57, n^o 4 (1 décembre 2012) : 1001–9. http://dx.doi.org/10.2478/v10172-012-0112-6.

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Dilatometric data for Astaloy CrM (3% Cr-0.5% Mo) and Astaloy CrL (1.5% Cr-0.2% Mo) powders with additions of 0.3% carbon and 3.0% manganese during sintering cycles up to 1120 and 1250°C in different atmospheres are reported. For comparison, also Astaloy CrM and Astaloy CrL powders were investigated. Starting with green densities of approx. 6.8 g/cm3, the final density of sintered compacts was influenced mainly by the sintering temperature, while the results showed the only minor effect of the sintering atmosphere on the final dimensional changes. However, the sintering atmosphere influences the sintering behaviour, microstructure and the final chemical composition of sintered compacts. In sintered and in the dilatometer cooled Mn-Cr-Mo-C steels predominantly bainitic structures were obtained.

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Mrvar, Primož, Milan Tribžan, Jožef Medved et Alojz Križman. « Study of the Eutectoid Transformation in the As-Cast Spheroidal Graphite Cast Iron with 'in Situ' Dilatation Analysis – Method for Quality Control ». Materials Science Forum 508 (mars 2006) : 287–94. http://dx.doi.org/10.4028/www.scientific.net/msf.508.287.

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The eutectoid transformation of the spheroidal graphite cast iron (S.G.I.) has been investigated with “in situ” dilatometer, which was made for the investigation of the cast iron alloys. The investigation of the eutectoid transformation has been taking place by evaluation of the “insitu” dilatation curves in connection with metallographic examinations, chemical analyses and thermodynamic calculations of the phase equilibriums. By dilatometric curves it is possible to follow the exact eutectoid transformation of austenite. On a basis of numerous quantitative relations, as the relation between the ferrite and pearlite fractions in the as-cast SGI, which was determined by the analysis of the dilatometric curves and the composition, the ratio between ferrite and pearlite in the microstructure could be determined in a very short time. From the kinetics of austenite transformation and temperature dependence of the ferrite or pearlite growth the following characteristic temperatures of the eutectoid transformation have been established: the ferrite nucleation o Tα , the beginning of the ferrite growth Tα , and pearlite growth Tp , respectively. Kinetic curves, which show the fraction of the single microstructure constituents in the microstructure in dependence of the transformation time for mainly ferrite SGI, are good represented by the physical sigmoidal Boltzmann model.

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Celin, Roman, et Jaka Burja. « Effect of cooling rates on the weld heat affected zone coarse grain microstructure ». Metallurgical and Materials Engineering 24, n^o 1 (2 avril 2018) : 37–44. http://dx.doi.org/10.30544/342.

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The effect of a cooling rate on the S690Q quenched and tempered steel welded joint coarse grain heat affected zone microstructure was investigated using a dilatometer with controlled heating and cooling fixture. Steel samples were heated to a peak temperature of 1350 °C and cooled at the different cooling time Dt8/5. A dilatometric analysis and hardness measurements of the simulated thermal cycle coarse grain samples were done. Transformation start and finish temperature were determined using dilatation vs. temperature data analysis. The microstructure of the sample with a cooling time 5 s consists of martensite, whereas at cooling time 80 s a bainitic microstructure was observed. The investigated steel cooling cycle using simulation approach makes possible to determine the range of an optimum CG HAZ cooling time for the welding.

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Zhang, Bao Xiang, Xiao Lu Gui, Gu Hui Gao, Zhun Li Tan et Bing Zhe Bai. « Investigation on the Austenitic Reverse Transformation of 0.2C-3Mn-1.7Si Steel with an Ultra-Slow Heating Rate ». Advanced Materials Research 1004-1005 (août 2014) : 214–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1004-1005.214.

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In order to clarify the austenite reverse transformation of a 0.2C-3Mn-1.7Si steel during intercritical region with an ultra-slow heating rate of 0.05°C/s, DIL (dilatometer), SEM, XRD and EPMA were carried out. The experimental results indicated that the dilatometric cures exhibited the shape of two “valleys” and the growth of austenite from quenched martensite was composed of three consecutive sub-stages. This phenomenon is associated with Mn-rich and Mn-poor regions in martensite matrix. During the heat treatment,the austenite forms firstly in region enriched in Mn. However, with increasing temperature, the growth of γ is restrained owing to the concentration of Si. Upon the further process of heating, the free energy for the reverse transformation increases, and the residual Mn-depleted regions start to transform at a higher temperature.

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Łazarska, Małgorzata, Tadeusz Z. Wozniak, Zbigniew Ranachowski, Andrzej Trafarski et Szymon Marciniak. « The Use of Acoustic Emission and Neural Network in the Study of Phase Transformation below MS ». Materials 14, n^o 3 (24 janvier 2021) : 551. http://dx.doi.org/10.3390/ma14030551.

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Acoustic emission and dilatometry were applied to investigate the characteristics of phase transformations in bearing steel 100CrMnSi6-4 during austempering below the martensite start temperature (MS 175 °C) at 150 °C. The aim of this study is to characterize the product of transformation occurring below the MS temperature using various research methods. Analysis of the dilatometric curves shows that, after the formation of athermal martensite below the MS temperature, the austenite continues to undergo isothermal transformation, indicating the formation of bainite. Additionally, tests were carried out with the use of acoustic emission during isothermal hardening of the adopted steel. The obtained acoustic emission signals were analyzed using an artificial neural network. The results, in the form of a graph of the frequency of acoustic emission (AE) event occurrence as a function of time, make it possible to infer about the bainite isothermal transformation. The results of this research may be used in the future to design optimal heat treatment methods and, consequently, may enable desired microstructure shaping.

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Król, Mariusz. « Solidification Characteristics of Mg-Li-Al Alloys ». Solid State Phenomena 275 (juin 2018) : 41–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.275.41.

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The six Mg-Li and Mg-Li-Al alloys in as-cast state namely Mg-4.5%Li, Mg-9%Li, Mg-12%Li, Mg-4.5%Li-1.5%Al, Mg-9%Li-1.5%Al and Mg-12%Li-1.5%Al were prepared and analysed. These alloys have been subjected to the thermal analysis (thermal derivative-analysis and dilatometry study), and the subsequent thermal assessment, mechanical properties and microstructures were studied. The heating and cooling dilatometric curves characterise by a linear reduction (alloys with 12wt.% of Li) and linear increase (alloys with 4.5wt.% of Li) in coefficient of linear thermal expansion as a function of temperature. No transitions in the solid state occur. Based on results of thermal derivative analysis a crystallisation process of Mg-Li and Mg-Li-Al alloys was proposed. Addition of aluminium in ultra-light Mg-Li alloys shows considerably improved strengthening without a reduction in grain size. Increasing the lithium content causes in an increase of hardness.

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Farahani, Hussein, Gerrit Zijlstra, Maria Giuseppina Mecozzi, Václav Ocelík, Jeff Th M. De Hosson et Sybrand van der Zwaag. « In Situ High-Temperature EBSD and 3D Phase Field Studies of the Austenite–Ferrite Transformation in a Medium Mn Steel ». Microscopy and Microanalysis 25, n^o 3 (12 avril 2019) : 639–55. http://dx.doi.org/10.1017/s143192761900031x.

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AbstractIn this research, in situ high-temperature electron backscattered diffraction (EBSD) mapping is applied to record and analyze the migration of the α/γ interfaces during cyclic austenite–ferrite phase transformations in a medium manganese steel. The experimental study is supplemented with related 3D phase field (PF) simulations to better understand the 2D EBSD observations in the context of the 3D transformation events taking place below the surface. The in situ EBSD observations and PF simulations show an overall transformation behavior qualitatively similar to that measured in dilatometry. The behavior and kinetics of individual austenite–ferrite interfaces during the transformation is found to have a wide scatter around the average interface behavior deduced on the basis of the dilatometric measurements. The trajectories of selected characteristic interfaces are analyzed in detail and yield insight into the effect of local conditions in the vicinity of interfaces on their motion, as well as the misguiding effects of 2D observations of processes taking place in 3D.

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Chandra, Amreesh, Dhananjai Pandey, M. D. Mathews et A. K. Tyagi. « Large negative thermal expansion and phase transition in (Pb1−xCax)TiO3 (0.30 ≤ x ≤ 0.45) ceramics ». Journal of Materials Research 20, n^o 2 (février 2005) : 350–56. http://dx.doi.org/10.1557/jmr.2005.0062.

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High-temperature dilatometric studies on (Pb1−xCax)TiO3 (x = 0.35, 0.35, 0.40, 0.45) ferroelectric ceramics reveal negative thermal expansion for x ≤ 0.40. The negative thermal expansion coefficient for x = 0.30, as obtained by dilatometry and powder x-ray diffraction, were found to be −8.541 × 10−6 K−1 and −11 × 10−6 K−1, respectively, which are comparable to those of other well-known negative thermal expansion materials like ZrW2O8, NaZr2(PO4)3. Results of temperature-dependent x-ray diffraction studies are also presented to show that the large negative thermal expansion behavior for x = 0.30 persists in a very wide range of temperatures, 70–570 K. Ca2+ substitution reduces the value of the negative thermal expansion coefficient of pure PbTiO3 crystal, but it enables the preparation of strong sintered ceramic bodies. The negative thermal expansion behavior is shown to disappear above the ferroelectric Curie point and is restricted to only the tetragonal compositions of (Pb1−xCax)TiO3.

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Zygmuntowicz, J., M. Piątek, M. Wachowski, P. Piotrkiewicz et W. Kaszuwara. « Thermoanalytical and dilatometric studies of the Al2O3–Cu–Mo hybrid composite ». Journal of Thermal Analysis and Calorimetry 142, n^o 1 (2 avril 2020) : 51–62. http://dx.doi.org/10.1007/s10973-020-09526-w.

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Abstract The present research is focused on the characterization of the composites from Al2O3–Cu–Mo system. The composites were prepared by slip casting method and subsequent sintering of green bodies in a reduced atmosphere. Two series of samples with different volume content of metallic powders were produced in the work: 10 vol% and 15 vol% of metal content with respect to the total solid-phase content. The sintering process of the composites was analyzed in detail. The linear shrinkage of the composites was measured. The shrinkage curves were obtained by dilatometry test in a heating mode. The composites were characterized by DTA/TG analyses and thermal conductivity. The composites were characterized by XRD, SEM, and EDX. The hardness was measured by Vickers hardness tester. Moreover, the Brazilian test was performed to determine the tensile mechanical properties of the composites. Fractography investigation was carried out as well. Dilatometric tests showed that the increase of the metallic phase volume in the ceramic matrix causes a decrease in the starting temperature of densification. Simultaneously, dilatometric experiments indicated that an increasing amount of metallic particles into the ceramic matrix increases the temperature of maximum densification and decreases the total shrinkage of the composites during sintering. The DTA/TG showed the characteristics of the dispersant decomposition to the atmosphere during thermal treatment and increase of mass connected with the oxidation of metals. Fractography results revealed good adhesion between Al2O3 matrix and the metallic phase. The observation allowed to conclude that the Al2O3 matrix surface is characterized by the brittle fracture mechanism.

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Slezak, Tomasz, Janusz Zmywaczyk, Piotr Koniorczyk et Lucjan Sniezek. « DSC Investigations of the Phase Transition in the High Strength Steel S960QL ». Advanced Materials Research 1126 (octobre 2015) : 148–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1126.148.

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Studies of the heat capacity temperature characteristics for microalloyed high strength steel S960QL is reported. The investigations were concentrated in the region of the second order phase transition. Experiments were carried out using the Differential Scanning Calorimeter DSC 404F1 Pegasus (Netzsch). As a tested material a sample from the high strength steel S960QL was used within temperature range of 50-1100 °C. In addition to this dilatometric investigations with the same temperature range as DSC ones were carried out using Netzsch dilatometer DIL 402C. Measurements of thermal characteristic, i.e. the heat capacity cp(T) and thermal expansion α*(T) were performed several times in order to observe thermal processes taking place in microalloyed high strength steel. Previous investigations have revealed the thermal hysteresis of the linear expansion in the region of the second order magnetic phase transition in the S960QL steel.

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Marchi, J., José Carlos Bressiani et Ana Helena A. Bressiani. « Sintering of Silicon Carbide Ceramics with Additives Based on the (Y₂O₃-Al₂O₃-SiO₂) System ». Advances in Science and Technology 45 (octobre 2006) : 1739–44. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1739.

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The sintering behavior of silicon carbide using alumina, silica and yttria as additives was investigated. Powders containing 90 vol. % SiC and 10 vol. % additives (keeping 1Y2O3:1Al2O3 molar ratio) were sintered at 1950°C/1h, in a dilatometer or a graphite resistance furnace. Thermal treatments were also done from 1500°C/1h up to 1800°C/1h, in order to evaluate the formation of transient crystalline secondary phases. The sintered samples were characterized through XRD, SEM and TEM analysis. The results showed that sintering behaviour is clearly related to the additive composition investigated, as demonstrated by linear shrinkages and linear shrinkages rate curves. Temperatures of particle rearrangment, solution-reprecipitation of SiC grains, as well as secondary crystalline phase(s) formation and dissolution could be revealed after dilatometric analysis. These temperatures are in good agreement with XRD results. Microstructural observations through SEM and TEM analysis are also related to the sintering behaviour.

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Idzior, Marek, et Wojciech Karpiuk. « Investigations of the Usefulness of Dilatometric Methods in the Diagnostics of Combustion Engines ». Energies 14, n^o 20 (15 octobre 2021) : 6703. http://dx.doi.org/10.3390/en14206703.

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Due to rapidly progressing development in the field of materials used in the automotive industry, research methods enabling the validation of the properties of materials used in specific applications, e.g., engines, are gaining importance. One such method is dilatometry, which belongs to a branch of physics dealing with methods of measuring the thermal expansion of bodies. It includes assessment study of the dependence of body measurements on external conditions. The authors propose that dilatometric methods could be used to diagnose damage and the causes of engine damage that has already occurred. This is a novel approach in diagnostic methods. The aim of the paper was to validate the proposed method for diagnosing of combustion engine components. Two cases of malfunction of this type of device are presented. In the first case, the subject of research is needle-nozzle holder precision pairs used in engines with a power of 150 kW. The main achievement of the research is revealing the occurrence of different thermal expansion values of the materials in the individual nozzle holders, with specific needles in particular causing adverse changes in clearances between these elements. The other case involved tests with respect to engine pistons. The proposed test method allows for a very accurate and relatively quick determination of the degree of damage to their surface. The conducted research confirms the usefulness of dilatometric methods in diagnosing combustion engines—their application makes it possible to determine the causes for the formation of the irregularities. The presented results are promising and enable further development of the methods and their implementation not exclusively with regard to internal combustion engines.

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Yang, Kun, Wei Hong Zheng et Jin Shu Cheng. « Effect of Li₂O on Viscosity and Thermal Expansion of Silicate Glass ». Advanced Materials Research 403-408 (novembre 2011) : 70–74. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.70.

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Subscript textViscosity, coefficient of thermal expansion, glass transition temperature and dilatometric softening temperature of soda-lime-silicate glass doped with Li2O were investigated by the rotating crucible viscometer and dilatometry, the melting temperature and activation energy for viscous flow of the studied melt were derived on the basis of Arrhenius Equation, in order to reveal the effects of Li2O on the properties of soda-lime-silicate glass. The results showed that the viscosity of soda-lime-silicate glass was effectively decreased and the melting temperature decreased from 1457°C to 1420°C with the increase of Li2O from 0 to 1.0wt%, furthermore, the Tgand Tsreduced 30~40°C. The ΔT responded to the range of viscosity of glass formation (η=103-107Pa•s) increased from 309.84°C to 313.45°C, and the activation energy for viscous flow decreased form 178.47 kJ•mol-1to 168.34 kJ•mol-1. The CTE α(25～400°C)of specimen doped with 0.4% Li2O was 92.048×10-6°C-1and the lowest of the samples.

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Prislupčák, Peter, Tibor Kvačkaj, Jana Bidulská, Pavol Záhumenský, Viera Homolová et Peter Zimovčák. « AUSTENITE – FERRITE TRANSFORMATION TEMPERATURES OF C MN AL HSLA STEEL ». Acta Metallurgica Slovaca 27, n^o 4 (7 décembre 2021) : 207–9. http://dx.doi.org/10.36547/ams.27.4.1306.

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The article is aimed to investigate a shift of transformation temperatures of C-Mn-Al HSLA steel with different cooling rates. The transformation temperatures from austenite to ferrite have been determined by dilatometry using thermal-mechanical simulator Gleeble 1500D. To define the start and finishing temperatures of the austenite-ferrite transformation intersectional method was used. Effect of cooling rate on transformation temperature has been evaluated for 0.17, 1, 5, 10, 15, 20, 25°C.s-1. There was found out that rising the cooling rate results in moving transformation temperature range to lower temperatures. The transformation temperatures have been also compared with temperatures calculated using equations of several authors. Some of them have considered cooling rates only. Cooling rates have effect on final microstructure. The effect has been evaluated by measuring hardness (HV10) relating the cooling rates from 0.17 to 25°C.s-1. Increasing cooling rates resulted in increase of hardness. Moreover, Thermo-Calc software was used to determine the Ae3 and Ae1 equilibrium temperatures. Equilibrium transformation temperatures Ae3-Ae1 were higher than experimentally measured by dilatometric method using Gleeble 1500D.

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Kawulok, Petr, Radek Jurča, Ivo Schindler, Stanislav Rusz, Rostislav Turoň, Petr Opěla et Rostislav Kawulok. « Laboratory Controlled Rolling of Microalloyed Steel for Production of Seamless Tubes ». Solid State Phenomena 258 (décembre 2016) : 611–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.611.

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Using the laboratory rolling mill with smooth rolls, piercing, as well as rolling in a pilger mill of the seamless tubes with diameter 273 mm from the HSLA steel microalloyed with vanadium steel was simulated. Influence of the wall thickness (6.3 – 40 mm) and finish rolling temperature on the final structural and mechanical properties was investigated. Necessary temperatures of the phase transformations in the course of cooling were determined by dilatometric tests. Based on the dilatometry results, finish rolling temperatures were reduced. Lower rolling temperatures yielded in a relative grain refinement. Effect of the finish rolling temperature did not have any marked impact on the tensile tests results. Strength properties decreased only slightly with the increasing wall thickness and the plastic properties were not influenced significantly by this parameter. The positive effect of the reduced finishing temperature appeared markedly in the results of impact tests performed at room temperature only. Notch toughness was increased by approx. 25 % in the case of the wall thickness of not less than 20 mm.

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Srinivasu, Chintalapati, Venkata G. K. M. Pisipati, Chadalavada R. Prabhu, Piratla Narayana Murty et Somayajula Lakshiminarayana. « Phase Transitions in p-(Phenyl Benzylidene)-p1-Alkylaniline Compounds : A Dilatometric Study ». Zeitschrift für Naturforschung A 62, n^o 1-2 (1 février 2007) : 75–83. http://dx.doi.org/10.1515/zna-2007-1-211.

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Dilatometric studies are carried out on liquid crystals (LCs), viz., p-(phenyl benzylidene)-p1- alkylanilines (PBnA for n = 7 - 10, 12, 14 and 16). LC PBnA compounds are found to exhibit four different types of phase variants. The lower homologues (for n = 3 - 6) exhibit an NBE trivariant, intermediate homologues (with n = 7 - 9) exhibit an NABE tetravariant, higher homologues (for n = 10 - 12) exhibit an ABE tetravariant, and long higher homologues (for n = 14 and 16) exhibit an AB bivariant phase sequence. Dilatometry studies in PBnA compounds infer the first order nature for IN (for n = 7, 8 and 9), IA (for n = 10, 12, 14 and 16), NA (for n = 8 and 9) and AB (for n = 14 and 16) phase transitions. Phase transitions involving the growth of the 3D smectic-B phase in PBnAs are found to be tuned by squeezing of orientational disorder. A comparative study of phase transitions exhibited by PBnA compounds is presented along with the data in other Schiff base compounds.

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Rao, M. Ramakrishna Nanachara, P. V. Datta Prasad, D. Madhavi Latha et V. G. K. M. Pisipati. « Dilatometric Study on Phase Transitions of Benzylidene-p-n-hexadecyl /Hexadecyloxy Anilines (5.O16, 5O.O16 and 5.16) ». Solid State Phenomena 181-182 (novembre 2011) : 67–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.181-182.67.

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Synthesis, characterization and phase transition studies (Dilatometry) have been carried out on three mesomorphic Schiff base compounds viz., N-(p-n-pentyl benzylidene)-p-n-hexadecyloxy aniline, 5.O16, N-(p-n-pentyloxy benzylidene)-p-n-hexadecyloxy aniline 5O.O16 and N-(p-n-pentyl benzylidene)-p-n-hexadecyl aniline, 5.16. The liquid crystalline phase identification and the phase transition temperatures have been carried out using SDTECHS polarising microscope attached with temperature controller with accuracy of ± 0.1 °C and for the conformation of the phase identification and the textures observed are compared with the standard textures. Further, the phase transition temperatures and the corresponding heats of transition across the phase transitions are recorded using DSC (Perkin Elmer). The characterization studies reveal that these compounds exhibit NG, N and A phase variants respectively. The nature of the phase transitions are studied through density results using dilatometric technique. The phase transitions exhibit first order nature in all the cases as expected. The results are discussed in the light of the body of the data available on other Schiff base compounds and on 5O.16.

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Chen, Peng, Ji Jun Yan, Chun Yu Shen, Yun Bo Xu et Guo Dong Wang. « Isothermal Bainite Transformation in Low Silicon TRIP Steel with Phosphorus Addition ». Materials Science Forum 788 (avril 2014) : 298–303. http://dx.doi.org/10.4028/www.scientific.net/msf.788.298.

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The low silicon transformation-induced plasticity (TRIP) steel with phosphorus addition is consisted of the microstructure of retained austenite, ferrite and bainite which produced by intercritical annealing and isothermal bainite transformation followed by rapid cooling. In this study, isothermal bainite transformation of different experimental parameters in low silicon TRIP steel with phosphorus addition was investigated in laboratory. The addition of cheap element phosphorus, which has the same effect of silicon in retard the kinetics of carbide formation during isothermal bainite transformation, can reduce the silicon content, improve surface quality, solve galvanizing problem and reduce costs. The effect of bainite isothermal temperature, intercritical annealing temperature and heating rates were investigated by dilatometric experiment on a push-rod Formastor-FII high-speed dilatometer with radio frequency induction heating. The high resolution observations, composition analysis and elements distribution of microstructure were carried out using the electron scanning microscopy of a field emission electron probe microanalyzer (JEOL JXA-8530F) operating at 20KV accelerating voltage.

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Selivanov, Evgeny N., O. V. Nechvoglod et R. I. Gulyaeva. « Thermal Expansion of Copper and Nickel Sulfides and their Alloys ». Defect and Diffusion Forum 334-335 (février 2013) : 55–59. http://dx.doi.org/10.4028/www.scientific.net/ddf.334-335.55.

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Thermal expansion coefficients of metal sulfides and their alloys are important for technological processes calculations of sulfide processing materials, for example, the crystallization equipment of nickel and copper-nickel converter matte. The synthesized copper and nickel monosulfide, and nickel and copper-nickel matte have been used as the initial samples. Dilatometric analysis was carried out by dilatometer (Linseis L78 RITA). Differences in the values measured are accounted for by the synthesis samples facilities, the coexistence of several non-stoichiometric sulfide phases and interaction during heating. In the temperature 20-500°C range the coefficients of thermal expansion (α) for the sulfides of copper, nickel and their alloys are changed from 10.4 to 20.610-6 1/K. Changes in the value α are accounted for by phase transitions in sulfide samples at their heating. Considering the properties of the phase components are an additive it is shown the thermal expansion coefficient complex sulfide-metal alloys is possible to calculate.

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Li, Zhiyong, Pengfei Li, Yang Luo, Xiyue Zhou, Liang Qi, Shengci Li et Zhigang Wang. « Effect of Austenitizing Temperature and Prior Martensite on Ultra-Fine Bainite Transformation Kinetics ». Metals 9, n^o 12 (5 décembre 2019) : 1309. http://dx.doi.org/10.3390/met9121309.

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An evaluation method for bainite transformation kinetics was established by theoretical derivation, dilatometric curve analysis, and microstructure observation. The isothermal transformation of ultra-fine bainite under different austenitizing temperatures and contents of prior martensite was studied using a DIL805L dilatometer. The kinetic parameters (activation energy Q*, autocatalytic factor λ, temperature rate constant κ, unit volume transformation rate, and the number density of nucleation sites Ni) of ultra-fine bainite transformation under different austenitizing temperatures and contents of prior martensite were calculated based on the displacement growth bainite dynamics model. It was found that the autocatalytic factor λ is linear with the austenite grain size d, and the number density of nucleation sites Ni is closely related to the average volume of the bainite subunit Vb. Moreover, the formation of prior martensite and its increase can increase the number of nucleation sites and the nucleation rate of the ultra-fine bainite; thus, the ultra-fine bainite transformation can be accelerated.

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Schuldt, Thilo, Martin Gohlke, Dennis Weise, Achim Peters, Ulrich Johann et Claus Braxmaier. « High-Resolution Dimensional Metrology for Industrial Applications ». Key Engineering Materials 437 (mai 2010) : 113–17. http://dx.doi.org/10.4028/www.scientific.net/kem.437.113.

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In this paper, we present the current status of our heterodyne interferometer with demonstrated noise levels below 5 pm/Hz in translation and below 10 nrad/Hz in tilt measurement, both for frequencies above 10-2 Hz. The interferometer, based on a highly symmetric design where reference and measurement beam have the same frequency and polarization, utilizes intensity stabilization and phaselock of the heterodyne frequency. Currently, we develop a new enhanced interferometer setup based on a mechanically and thermally highly stable glass ceramic. While the interferometer was developed with respect to the specific requirements of the LISA (Laser Interferometer Space Antenna) space mission, it is also the basis for applications in high-precision dilatometry and industrial metrology. We present a prototype dilatometer with which we measured the coefficient of thermal expansion (CTE) of carbon-fiber reinforced plastic (CFRP) with an accuracy below 10-7/K. For surface property measurements, we develop an actuation of the measurement beam over the surface under investigation.

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Грешта, Виктор Леонидович, Дарья Владимировна Ткач, Александр Владимирович Климов, Евгений Георгиевич Сотников et Зоя Васильевна Леховицер. « ДОСЛІДЖЕННЯ ВПЛИВУ ЛЕГУВАННЯ НА ТЕМПЕРАТУРНИЙ КОЕФІЦІЄНТ ЛІНІЙНОГО РОЗШИРЕННЯ ПОКРИТТІВ ». Aerospace technic and technology, n^o 7 (10 novembre 2018) : 81–87. http://dx.doi.org/10.32620/aktt.2018.7.12.

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The effect of doping with yttrium-containing ligatures on the thermal coefficient of the linear expansion of sealing coatings is studied. KHA-82 coating was taken as the base material for the research. It is used in the aircraft engines produced by Motor Sich JSC. This coating contains nickel (base), silicon, aluminium, and solid lubricants (graphite and boron nitride). To enhance the physical-mechanical properties of the coating, an yttrium-containing ligature was added to the size prepared by the serial process. Three different compositions of the ligature with varying content of yttrium were studied, namely Ni-Y is composition No.1, Y is composition No. 2, Co-Ni-Cr-Al-Y is composition No. 3, and KHA-82 is composition No. 4. The coatings were applied onto specially prepared samples by a gas-flame technique. Analysis of the volumetric and possible structural phase changes in the material of the coatings under consideration was carried out on the Shevenar differential dilatometer. It was found out that during the first heating within 650-700° C, there is a change in the shape of the dilatometric curve. Recurring heating also causes the change in the trajectory of the dilatometric curve. The obtained result is probably related to the development of the oxidization processes, appearance of intermetallide phases, and changes in the porosity of the coatings during the first and recurring heating. Reduction of the pore space is beneficial in terms of energy as it is accompanied by the reduction of free surface, which in its turn can trigger the development of phase changes that are connected with the formation of oxide, nitride, and intermetallide inclusions. The smallest difference in the shape of dilatometric curves is observed in the coating of composition No. 3, which is presumably due to the fact that double spinels with a more compact structure are formed in the structure of the material obtained. The estimation of the difference in the temperature coefficient of the linear expansion of the base and coating materials indicates an insignificant difference in these values that can be reduced if the suggested yttrium-containing ligatures are added.

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Crozet, Coraline, Annie Antoni Zdziobek, Sabine Lay et Stéphane Coindeau. « Influence of Copper Additions in Fe-10Ni (mass %) Alloys on Cooling Microstructures ». Solid State Phenomena 172-174 (juin 2011) : 505–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.505.

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Austenite/ferrite phase transformations in Fe-xCu-10Ni alloys, 0<x<15 (mass%), are studied under two different cooling conditions, ice-brined quenching or slow cooling in the dilatometer. The influence of copper addition and cooling rate on the microstructure of the alloys is studied. Metallographic examinations of quenched samples show that metastable transformations occur during cooling. As for Fe-Ni alloys, it is impossible to stabilize the high temperature phase (γFeNi) in the Fe-Ni-Cu alloys. Dilatometry measurements of the γ → α transformation temperature with a cooling rate of 2°C/min also indicate a metastable phase formation despite the low cooling rate. For all alloys, a mixture of massive and lath ferrite is observed, one being predominant depending on the cooling conditions and composition. It is shown that the cooling rate has nearly no influence on the microstructure of alloys with a small amount of Cu unlike the alloys containing more Cu. In all alloys containing Cu, nanometric γCu precipitates, much finer in the quenched samples, are detected in the ferrite grains.

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RoŻniata, E., et R. Dziurka. « The Phase Transformations in Hypoeutectoid Steels Mn-Cr-Ni ». Archives of Metallurgy and Materials 60, n^o 1 (1 avril 2015) : 497–502. http://dx.doi.org/10.1515/amm-2015-0080.

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Abstract The results of a microstructure and hardness investigations of the hypoeutectoid steels Mn-Cr-Ni, imitating by its chemical composition toughening steels, are presented in the paper. The analysis of the kinetics of phase transformations of undercooled austenite of steels containing different amounts of alloying elements in their chemical composition, constitutes the aim of investigations. Metallographic examinations were carried out on a Axiovert 200 MAT light microscope. Sections were etched with a 3% HNO3 solution in C2H5OH. Dilatometric tests were performed using L78 R.I.T.A dilatometer. Using dilatometer the changes of elongation (Δl) of the samples with dimensions Ø 3×10 mm as a function of temperature (T) were registered. Obtained heating curves were used to precisely determine the critical temperatures (critical points) for the tested steels, while the differentiation of obtained cooling curves allowed to precisely define the temperatures of the beginning and the end of particular transition to draw CCT diagrams. Four CCT diagrams worked out for the tested hypoeutectoid steels (for quenching of steel) are - in the majority of steels - separated by the undercooled austenitic range and are of the letter „C” shape. However, for steels with Mn and Ni the separation of diffusive transformations from the bainitic transformation by the stable austenitic range is not observed. Hardenability of four investigated hypoeutectoid steels is similar, but still not high. To obtain martensite in the microstructure of these steels, it is necessary to apply the cooling rate higher than 25°C/s. The exception constitutes the Mn - Ni steel, in which only cooling with the rate higher than 50°C/s allows to achieve the martensitic microstructure and to avoid diffusive transformations (pearlitic and ferritic).

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