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Journal articles on the topic 'Ageing response hardness'

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Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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1

Nur Hidayah, A. Z., J. B. Shamsul, K. R. Ahmad, A. A. Sinar, and Ahmad Mujahid Ahmad Zaidi. "Ageing Response of Powder Metallurgy AZ91 and AZ91 Reinforced with Multiwall Carbon Nanotube." Materials Science Forum 857 (May 2016): 261–65. http://dx.doi.org/10.4028/www.scientific.net/msf.857.261.

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Powder metallurgy metal matrix composites based on AZ91 alloy matrix reinforced with 0.3, 0.6 and 0.9 weight percent of multiwall carbon nanotube (MWCNT) were investigated from the point of view of their response to artificial ageing as compared to the unreinforced AZ91 matrix alloy. Mg-Zn-Al (AZ91) and its composite were prepared by milling the raw materials and followed by sintering at 450°C for 2 hours. The sintered samples were solution treated at 415°C for 2 hours and followed by artificial ageing at 175°C. The ageing behavior was monitored by following the phase analysis and hardness of the samples examined. Microstructure of the sintered composites indicated that MWCNT was embedded in the AZ91 matrix alloy. All composites indicated lower hardness than matrix, however AZ91reinforced with 0.6 and 0.9 weight percent of CNT showed accelerated ageing. X-ray diffraction pattern indicated the present of β-phase (Mg17Al12) that responsible for the hardening behavior.
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2

Yan, Yong, Ze Qin Liang, and John Banhart. "Influence of Pre-Straining and Pre-Ageing on the Age-Hardening Response of Al-Mg-Si Alloys." Materials Science Forum 794-796 (June 2014): 903–8. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.903.

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The effect of pre-straining and pre-ageing on the age hardening response of Al-0.6%Mg-0.8%Si alloy is studied by Vickers hardness and differential scanning calorimetry (DSC). It is found that pre-ageing can suppress the formation of unwanted clusters and keeps the structure stable for a certain time. A pre-ageing treatment can effectively reduce or avoid the negative effect of natural ageing on artificial ageing and even produce a positive effect. Cluster formation can also be reduced by pre-straining, but the kinetics of clustering is still similar to that of the as-quenched condition. In contrast, after pre-straining, the peak positions of β and β move to lower temperatures and peak hardness is achieved in a shorter time, indicating that the formation of β and β is accelerated by pre-straining. However, the negative effect of natural ageing still persists after pre-straining. Pre-straining before pre-aging can take advantage of both techniques and produce a positive strength response. For pre-straining after pre-aging, pre-straining tends to destabilize the structure created by pre-ageing and can reactivate the clustering process, which has negative effect on subsequent artificial ageing.
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3

Chen, Zhong Wei, Li Fan, and Pei Chen. "Early Age Hardening Response of Al-Cu-Mg Alloys." Advanced Materials Research 146-147 (October 2010): 1327–30. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1327.

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The early age hardening behavior in Al-Cu-Mg alloys with fixed Cu content (0.50 wt%) and varying amounts of Mg has been studied by hardness tests and TEM observation. Two alloys both exhibit the early rapid hardening phenomenon based on large solute-aggregates analysis. Ageing time of early stage rapid hardening of Al-0.5Cu-1.99Mg alloys is less than that of Al-0.5Cu-1.48Mg alloys. For two alloys, ageing time of early stage rapid age hardening reduces with artificial ageing temperature increasing. The early stage rapid age hardening is depended on the composition and artificial ageing temperature. Forming larger solute-aggregates may give rise to early rapid age hardening.
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4

Cao, Ling Fei, Paul A. Rometsch, Hao Zhong, and Barry C. Muddle. "Effect of Pre-Ageing on the Artificial Ageing Response of Al-Mg-Si(-Cu) Alloys." Materials Science Forum 654-656 (June 2010): 918–21. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.918.

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The effect of different pre-ageing treatments on the subsequent artificial ageing response of Al-Mg-Si(-Cu) alloys have been investigated using hardness, tensile and electrical conductivity testing. The microstructural evolution was characterised by differential scanning calorimetry (DSC) and 3-dimensional atom probe (3DAP) analysis. Pre-ageing treatments were carried out at 160-250°C for short times. Results show that the early stage artificial ageing response after 30 minutes at 170°C is strongly influenced by the pre-ageing and natural ageing conditions. A pre-ageing treatment performed for a short time at a high temperature and within a short delay after solution treatment and quenching was found to give a promising hardening response during subsequent artificial ageing. The mechanisms by which pre-ageing can reduce the detrimental effect of natural ageing on the artificial ageing response will be discussed in relation to the formation and distribution of clusters, GP zones and/or precipitates.
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5

Zhong, Hao, Bin Liao, Xiao Dong Wu, Ling Fei Cao, and Paul A. Rometsch. "Development of Al-Mg-Si-(Cu) Alloys for Automotive Body Panels and the Related Ageing Behaviours." Materials Science Forum 879 (November 2016): 279–83. http://dx.doi.org/10.4028/www.scientific.net/msf.879.279.

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In this work, Al-Mg-Si-Cu alloys for automotive body panels were designed and the related ageing behaviours were discussed in detail to help understand natural ageing and pre-ageing, as well as their influence on the subsequent paint-bake response. The clustering behavior of these Al-Mg-Si-Cu alloys in different ageing conditions was investigated by hardness / yield strength and electrical conductivity testing. The microstructure was investigated by using Electron Backscattered Diffraction (EBSD) technique, along with Scanning Electron Microscopy with Backscattered Electron Detector (BSE). The results show that the paint bake response is strongly influenced by the pre-ageing and natural ageing conditions. Both alloys show serrated yielding in a short natural ageing condition. Immediate high-temperature pre-ageing treatments were found to give a promising hardening response during the subsequent artificial ageing/ paint baking at 170oC.
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6

Nurcahyaningsih, Dwi Ayu, Risly Wijanarko, Irene Angela, and Bondan Tiara Sofyan. "Effect of Ti Addition to Age Hardening Response of Al-10Zn-6MgxTi Alloy Produced by Squeeze Casting." MATEC Web of Conferences 186 (2018): 02009. http://dx.doi.org/10.1051/matecconf/201818602009.

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This research focused on investigating the effects of Ti addition on the age hardening response of Al 7xxx alloy for Organic Rankine Cycle (ORC) turbine impeller application in power plant generators. Al-10Zn-6Mg wt. % alloys were produced by squeeze casting with 0.02, 0.05, and 0.25 wt. % Ti addition. As-cast samples were homogenized at 400 °C for 4 h. Solution treatment was conducted at 440 °C for 1 h, followed by quenching and ageing at 130 °C for 200 h. Age hardening result was observed using Rockwell B hardness measurement. Other characterizations included impact testing, STA, optical microscopy, and SEM-EDS. Results showed that the addition of Ti in all content variations increased the as-cast hardness due to the diminution of secondary dendrite arm spacing (SDAS) values of the alloy. Ageing at 130 °C strengthened the alloys, however the addition of Ti was not found to affect neither peak hardness nor impact values of the alloy. Identities of second phases formed during solidification were found to be T (Mg32(Al,Zn)49), β (Al8Mg5), and TiAl3, while precipitates produced during ageing were GP Zone, η′, and η (MgZn2).
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7

Aiza Jaafar, C. N., I. Zainol, and Mohd Amirul Zalif Mohamad Sapri. "The Effects of Thermal Ageing on Properties and Microstructure of Al-6063 Alloy." Key Engineering Materials 694 (May 2016): 111–15. http://dx.doi.org/10.4028/www.scientific.net/kem.694.111.

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The effect of thermal ageing on the properties and microstructure of Al-Mg-Si alloy was investigated. In this work, an extruded Al-6063 alloy samples were used as the main materials. In order to study the effect of thermal ageing, the alloy samples were solution treated at 530 °C and then quenched into water before artificially aged at elevated temperatures between 120 and 250 °C. The ageing response and mechanical properties was monitored by Vickers hardness and tensile tests, respectively. The analysis of surface fracture and microstructure of peak aged alloy were carried out by means of scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. Result shows that the highest hardness value and tensile properties is gained by the alloy that aged at 120 °C. It is found that increasing in hardness and strength values of the alloy are due to precipitates formation during thermal ageing. Fracture analysis on peak-aged condition indicates that the alloy having more ductility after thermal ageing. The result shows that the higher ageing temperature will lead to the higher ductility of the Al-6063 alloy, as a results the alloy’s strength is reduced.
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8

Gardner, H. M., A. Radecka, D. Rugg, D. E. J. Armstrong, M. P. Moody, and P. A. J. Bagot. "The Role of Oxygen in α2 Formation in the Titanium Model Alloy Ti-7Al." MATEC Web of Conferences 321 (2020): 04003. http://dx.doi.org/10.1051/matecconf/202032104003.

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The mechanical and microstructural response of a model Ti-7wt.%Al alloy doped with 500 wppm oxygen has been examined in detail as a function of ageing. Three ageing conditions, ice-water quenched, and aged at 550 oC for 10 or 49 days were examined in detail as a function of ageing. Nanoindentation was used to measure hardness as a function of ageing, while Atom Probe Tomography (APT) also revealed α2 precipitation in the aged samples. The partitioning pReference of oxygen to the α matrix instead of the α2 precipitates has been directly measured.
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9

Chauke, Levy, Pfarelo Daswa, Heinrich Möller, and Gonasagren Govender. "The Effect of Natural Pre-Ageing on the Mechanical Properties of Rheo-High Pressure Die Cast Aluminium Alloy 2139." Materials Science Forum 828-829 (August 2015): 244–49. http://dx.doi.org/10.4028/www.scientific.net/msf.828-829.244.

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Near-net shape casting of wrought aluminium alloys has proven to be difficult due to hot tearing. The Council for Scientific and Industrial Research (CSIR) has successfully processed wrought aluminium alloy 2139 into plate castings using the Rheo-high pressure die casting process (R-HPDC). Alloy 2139 is a Ag-containing aluminium alloy from the Al-Cu-Mg 2xxx series family. The addition of Ag enhances the age hardening response through the formation of co-clusters that act as precursors to the formation of plate-like Ω precipitates. These co-clusters typically form during natural ageing and 12-24 h of natural pre-ageing is normally specified before artificial ageing in Ag-containing Al-Cu-Mg alloys. The T6 hardness and tensile properties of R-HPDC 2139 alloy were investigated with and without natural pre-ageing. It is shown that there is no significant difference in both peak hardness and tensile properties in R-HPDC alloy 2139 with and without natural pre-ageing. The possible precipitation phenomena in both cases are discussed.
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10

Jauhari, Inas M., Danny Taufik Bahar, Syarah Khayrun Nisa, and Bondan Tiara Sofyan. "Effects of Cu Addition on Age Hardening Response of Al-7Si-4Mg Alloys at 130 °C." Key Engineering Materials 833 (March 2020): 74–79. http://dx.doi.org/10.4028/www.scientific.net/kem.833.74.

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The effects of Cu addition of 0.38, 3.82, and 6 wt. % in Al-7Si-4Mg alloy on hardness and age hardening response were discussed. Samples were solution treated at 495 °C for 2 h, quenched, and aged at 130 °C for 0 to 498 h. Characterization included hardness test, microstructural observation by an optical microscope (OM) and Scanning Electron Microscope (SEM) combined with Energy Dispersive X-Rays Spectroscopy (EDX), as well as Simultaneous Thermal Analysis (STA) testing. The results showed an increased in as-cast hardness along with addition of Cu. Peak hardness increased to 64.47, 65.8, and 70.1 HRB by addition of 0.38, 3.82, and 6 wt. % Cu, respectively. The addition of Cu promoted the formation of Al2Cu and Al5Cu2Mg8Si6 which contributed to higher as-cast hardness. Formation of GP-zone, θ”, and θ’ was observed after ageing at 48, 240, and 290 °C, respectively and no effects of Cu was detected on the formation temperatures of the precipitates.
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11

Mehta, Bharat, Arvid Svanberg, and Lars Nyborg. "Laser Powder Bed Fusion of an Al-Mg-Sc-Zr Alloy: Manufacturing, Peak Hardening Response and Thermal Stability at Peak Hardness." Metals 12, no. 1 (December 27, 2021): 57. http://dx.doi.org/10.3390/met12010057.

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This study shows a rapid and systematic approach towards identifying full density and peak hardness for an Al-Mg-Sc-Zr alloy commonly known as Scalmalloy®. The alloy is tailored for the laser powder bed fusion process and has been shown to be printable with >99.8% relative density. The microstructure suggests Al grain refinement in melt pool boundaries, associated with formation of primary Al3(Sc,Zr) particles during solidification. Peak hardening response was identified by heat treatment tests at 573,598 and 623 K between 0 and 10 h. A peak hardness of 172 HV0.3 at 598 K for 4 h was identified. The mechanical properties were also tested with yield and ultimate strengths of 287 MPa and 364 MPa in as-printed and 468 MPa and 517 MPa in peak hardened conditions, respectively, which is consistent with the literature. Such an approach is considered apt when qualifying new materials in industrial laser powder bed fusion systems. The second part of the study discusses the thermal stability of such alloys post-peak-hardening. One set of samples was peak hardened at the conditions identified before and underwent secondary ageing at three different temperatures of 423,473 and 523 K between 0 and 120 h to understand thermal stability and benchmark against conventional Al alloys. The secondary heat treatments performed at lower temperatures revealed lower deterioration of hardness over ageing times as compared to the datasheets for conventional Al alloys and Scalmalloy®, thus suggesting that longer ageing times are needed.
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12

Zhang, Xingpu, Meng Liu, Jiangwei Wang, Jixue Li, and John Banhart. "Combined effect of Sn addition and pre-ageing on natural secondary and artificial ageing of Al–Mg–Si alloys." Journal of Materials Science 57, no. 3 (January 2022): 2149–62. http://dx.doi.org/10.1007/s10853-021-06654-y.

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AbstractBoth Sn addition and pre-ageing are known to be effective in maintaining the artificial ageing potential after natural ageing of Al–Mg–Si alloys. In this study, the combined effects of Sn addition and pre-ageing at 100 °C or 180 °C on natural secondary ageing and subsequent artificial ageing of an alloy AA6014 were investigated using hardness, electrical resistivity, differential scanning calorimetry and transmission electron microscopy characterizations. It is found that pre-ageing can suppress natural secondary ageing and improve the artificial ageing hardening kinetics and response after 1 week of natural secondary ageing in both alloys with and without Sn addition. The effect of pre-ageing at 100 °C is more pronounced in the Sn-free alloy while the combination of pre-ageing at 180 °C and adding Sn shows superiority in suppressing natural secondary ageing and thus avoiding the undesired hardening before artificial ageing. Moreover, when natural ageing steps up to 8 h are applied before pre-ageing at 100 °C, the effect of pre-ageing in Sn-added alloy can be further improved. The influence of Sn on vacancies at different ageing temperatures is discussed to explain the observed phenomena. Graphical abstract
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13

Taute, Carlien, and Heinrich Möller. "Age-Hardening of Rheo-High Pressure Die Cast Al-Alloy 6066." Advanced Materials Research 1019 (October 2014): 47–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1019.47.

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Al-Mg-Si-Cu alloy 6066 is a heat-treatable wrought alloy that is commonly used in high performance bicycle frames. Wrought alloys are difficult to cast using conventional liquid casting techniques, as hot tearing can occur. However, a method that effectively reduces that risk is rheo-high pressure die casting (R-HPDC). Casting alloy 6066 using semi-solid metal processing makes it possible to be used for near-net shape forming of components. This study investigates the age-hardening response of R-HPDC alloy 6066. The effects of different solution heat treatments, natural pre-ageing and artificial ageing are studied. The different solution heat treatments investigated are a one-step and a two-step solution treatment. The one-step treatment was performed at 530°C only and the two-step treatment at 530°C followed by 550°C. It is shown that natural pre-ageing has a detrimental effect on the T6 properties and that the longer two-step solution heat treatment is justified due to an increase in hardness and prevention of incipient melting. The Vickers hardness in different temper conditions (F, T4, T5 and T6) were determined and compared to the typical hardness values of the alloy in the wrought condition.
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14

Sjölander, Emma, Salem Seifeddine, and Federico Fracasso. "Influence of Quench Rate on the Artificial Ageing Response of an Al-8Si-0.4Mg Cast Alloy." Materials Science Forum 828-829 (August 2015): 219–25. http://dx.doi.org/10.4028/www.scientific.net/msf.828-829.219.

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The aim of the study is to present the influence of quench rate on the artificial ageing response of Al-8%Si-0.4%Mg cast alloy in terms of Brinell hardness and yield strength. The investigated material was produced by a gradient solidification technique and exhibited a microstructure that corresponds to the one of gravity die castings, with a dendrite arm spacing of approximately 25 µm. The study comprises two solution treatment temperatures, five quench rates and artificial ageing times exceeding 100 hours at 170 and 220 °C. The microstructure and concentration profiles of Mg and Si were evaluated using energy and wavelength dispersive spectroscopy. Microstructural examination reveals an increment of solutes in the Al-matrix when higher solution treatment temperatures accompanied with high quench rates are applied and shows how both Si and Mg atoms have diffused towards the eutectic during quenching. Consequently, i.e. by increasing the levels of solutes and vacancies, the highest strength levels were realized. The study confirmed that quench rates above 2 °C /s do not offer substantial strength improvement while quenching at lower rates resulted in a lower peak hardness and longer times to peak
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15

Shankar, Gowri, U. Achutha Kini, and Sathya Shankar Sharma. "Process Optimization on Hardness of Precipitation Hardened Al6061 Alloy Using Design of Experiments." Materials Science Forum 909 (November 2017): 27–32. http://dx.doi.org/10.4028/www.scientific.net/msf.909.27.

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Aluminium is ranked after iron and steel in the metal market. Aluminium 6061 alloy has been selected by many designers and engineers for different kind of applications. Further, its strength can be improved by cold working, refinement of grains, precipitation and dispersion hardening. In this work, trials are conducted for the investigation of the effects due to age hardening parameters like, solutionizing time, temperature and time for aging on hardness of 6061 Aluminium alloy using Design of Experiments. The response is predicted by using linier regression model. From the results it can be perceived that, the ageing temperature and aging time have a substantial effect on the response whereas, solutionizing time does not have a significant effect. For a specific set of parameters the hardness is improved from 50 to 74 BHN, resulted in an increase in hardness by about 50%.
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16

Stenqvist, Torkel, Kristoffer Bång, Sören Kahl, Arnaud Contet, and Oskar Karlsson. "Ageing of Brazed Aluminium AA6xxx Alloys for Vehicle Radiators." Materials Science Forum 794-796 (June 2014): 1239–44. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.1239.

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Some aluminium alloys with Mg-Si age-hardening are used in vehicle radiators. For cost reasons they are preferably delivered in a naturally aged temper. Estimated minimum time of natural ageing between brazing and when the radiator is taken into service is 14 days. At the service temperature of 95°C, the radiator material will continue to age harden. For accelerated durability testing it is vital to use a radiator with the strength and ageing response of a service radiator. We investigated whether the full 14 days of natural ageing were needed, or if the time could be shortened. Since a vehicle is not in constant use, the radiator temperature will vary over time. We therefore compared cyclic ageing between ambient temperature and 95°C to continuous ageing at 95°C. The Sapa Heat Transfer alloys FA7870 (for headers) and FA7850 (for tubes) were subjected to different ageing times at different temperatures. Tensile and hardness were performed to assess the ageing effect. It was found that natural ageing reduced hardening during the subsequent ageing at service temperature ageing effect, an effect that was most pronounced for the first four days. There was no difference between continuous and cyclic ageing.
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17

Liu, Hong Wei, Feng Wang, Bai Qing Xiong, Yon Gan Zhang, Zhi Hui Li, and Xi Wu Li. "Ageing Precipitation and Strengthening Behavior of the Spray Formed Al-Zn-Mg-Cu Alloy." Advanced Materials Research 535-537 (June 2012): 903–8. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.903.

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In this study, the Al-Zn-Mg-Cu alloy was prepared by spray forming process. The ageing precipitation and strengthening behavior of the spray formed Al-Zn-Mg-Cu alloy were studied by microhardness tests, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) .The results show that the main strengthening precipitates of the spray formed Al-Zn-Mg-Cu alloy are GPI (solute-rich clusters), GPII (vacancy-rich clusters) under peak aging condition. The effect of the microstructure on ageing hardness is controlled by the size and amount of the existing precipitates, and therefore depends critically on the ageing temperature and ageing time. Strength of this alloy is influenced significantly during natural ageing at room temperature, which is related to the dominant formation of GPI. During the initial stage of artificial ageing at 120°C, strong age-strengthening response is due to the formation of GP zones (both GPI and GPII ) .During later stages of artificial ageing , GPII precipitation is accelerated significantly but GPI is not affected clearly.
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18

Katrenipadu, Srinivasa Prasad, and Swami Naidu Gurugubelli. "Regression Modeling and Experimental Investigations on Ageing Behavior of Nano-Fly Ash Reinforced Al-10wt%Mg Alloy Matrix Composites." International Journal of Surface Engineering and Interdisciplinary Materials Science 6, no. 2 (July 2018): 36–49. http://dx.doi.org/10.4018/ijseims.2018070103.

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Nano-fly ash particles reinforced Al-10wt%Mg alloy matrix composites produced by stir-casting method were tested for their ageing response. Ageing studies were performed at 160 °C, 200 °C and 240 °C temperatures and a maximum peak hardness of 142 VHN was observed during ageing at 200 °C for the composite with 10 wt% nano fly ash reinforcement. This is due to rapid nucleation and growth of βI particles at this temperature. Experiments were designed for different compositions and different ageing temperatures on the basis of the Design of Experiments technique. The factorial design is considered to improve the reliability of results and to reduce the size of experimentation without loss of accuracy. A model to predict the ageing behaviour of the composites was developed with the terms of 5, 10 and 15% weight fraction of fly ash at 160 °C, 200 °C and 240 °C ageing temperatures. The developed regression model was validated by statistical software MINITAB-R17.1.0. It was found that the developed regression model could be effectively used to predict the ageing behavior at 95% confidence level.
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19

Zuiko, Ivan, Marat Gazizov, and Rustam Kaibyshev. "Effect of Cold Plastic Deformation on Mechanical Properties of Aluminum Alloy 2519 After Ageing." Materials Science Forum 794-796 (June 2014): 888–93. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.888.

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Effect of cold plastic deformation prior to ageing at 180°C on a microstructure and mechanical properties at room temperature for an AA2519 alloy was examined subjected to solution treatment and water quenching initially. It was found that cold rolling with a reduction of 15% or equal-channel angular pressing (ECAP) up to a true strain of ~1 leads to acceleration of age-hardening response of this alloy. Peak hardness values of 127, 175 and 169 HV0.2were achieved by ageing following quenching, cold rolling and ECAP, respectively. The highest values of yield stress (YS) of 475 MPa and ultimate tensile strength (UTS) of 520 MPa, were attained after ECAP followed by ageing. The effect of cold plastic deformation prior to ageing on the precipitation behavior and its relation with mechanical properties of the AA2519 is discussed.
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20

Sekunowo, O. I., G. I. Lawal, and S. O. Adeosun. "Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions." Journal of Metallurgy 2012 (December 11, 2012): 1–7. http://dx.doi.org/10.1155/2012/921235.

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Samples of the 6063 (Al-1.09Mg2Si) alloy ingot were melted in a crucible furnace and cast in metal and sand moulds, respectively. Standard tensile, hardness, and microstructural test specimens were prepared from cast samples, solution treated at 520∘C, soaked for 6 hrs, and immediately quenched at ambient temperature in a trough containing water to assume a supersaturated structure. The quenched specimens were then thermally aged at 175∘C for 3–7 hrs. Results show that at different ageing time, varied fractions of precipitates and intermetallics evolved in the specimens’ matrices which affect the resulting mechanical properties. The metal mould specimens aged for four hours (MTA-4) exhibited superior ultimate tensile strength of 247.8 MPa; microhardness, 68.5 HV; elongation, 28.2% . It is concluded that the extent of improvement in mechanical properties depends on the fractions, coherence, and distribution of precipitates along with the type of intermetallics developed in the alloy during ageing process.
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21

Sun, Wei Bing, and Cu Ming Liu. "Influence of a Trace Alloying of Ag on the Ageing Behavior and Mechanical Properties of AZ80M Magnesium Alloys." Materials Science Forum 849 (March 2016): 154–61. http://dx.doi.org/10.4028/www.scientific.net/msf.849.154.

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The ageing behavior of AZ80+xAg (x=0;0.3;0.5) magnesium alloys at different temperature were systematically investigated using optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Experimental results demonstrate that the trace amount of Ag accelerated the precipitation of Mg17Al12 phase during ageing at 200°C, AZ80+0.5Ag achieved the peak hardness of 89.7HV after holding for 12h, compared with 80.8HV after 28h for the Ag-free alloy. However, when ageing at high temperature (250°C), the promotion response of Ag was totally vanished. The tensile property of the peak aged alloys at ambient temperature increased with Ag addition, as well as the tensile property at elevated temperature. Further investigation indicates that Ag addition suppresses the discontinuous precipitates, which account for the enhanced property of Ag-containing alloy.
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22

Gao, Nong, Marco J. Starink, Minoru Furukawa, Z. Horita, Cheng Xu, and Terence G. Langdon. "Evolution of Microstructure and Precipitation in Heat-Treatable Aluminium Alloys during ECA Pressing and Subsequent Heat Treatment." Materials Science Forum 503-504 (January 2006): 275–80. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.275.

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The precipitation and evolution of microstructure in a spray-cast Al-7034 alloy and a commercial wrought Al-2024 alloy were studied after equal-channel angular pressing (ECAP) using transmission electron microscopy and differential scanning calorimetry (DSC). Microstructural examination showed the grain sizes of both alloys were reduced to the range of ~0.3–0.5 μm through ECAP. The DSC analysis identified the occurrence of thermal effects involving the formation, coarsening, dissolution and melting of the precipitate phases and concurrent recrystallization. The heating and ageing response of the alloys processed by ECAP was identified by micro-hardness testing of the samples after interrupted heating and ageing treatments.
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23

Rivolta, Barbara, Riccardo Gerosa, Marco Boniardi, and Andrea Casaroli. "On the peak strength of 7050 aluminum alloy: mechanical and corrosion resistance." Frattura ed Integrità Strutturale 16, no. 60 (March 25, 2022): 273–82. http://dx.doi.org/10.3221/igf-esis60.19.

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This work consists of an experimental study on the ageing response and resulting properties of AA7050 plate material. New heat treatments are investigated for achieving a peak-aged temper, as a T6 temper may be said to be, that achieves yield and tensile strengths superior to those of the documented T7 treatments. For this alloy, the Standard establishes T7X tempers which were developed to obtain a very good compromise between mechanical strength and corrosion resistance. Nevertheless, for all those applications in which the environment is not considered critical for corrosion behaviour, the peak strength condition could be beneficial. In this experimental work, the authors use standard hardness testing to investigate mechanical response as a function of ageing time at several ageing temperatures, all applied immediately after solution. Upon identifying specific times and temperatures of interest, specimens aged under the selected treatments were subjected to tensile testing and intergranular corrosion testing. The results show that a single-step ageing heat treatment is able to produce a significantly high both yield and ultimate tensile strength. Moreover, the corrosion test data indicates that this new heat treatment produces corrosion resistance similar to that of the T76 heat treatment.
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24

SONG, XIPING, LONG CHEN, KUN LI, and GUOLIANG CHEN. "EFFECT OF CARBON AND OXYGEN ADDITIONS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti-4.3Fe-7.1Cr-3Al ALLOY." International Journal of Modern Physics B 23, no. 06n07 (March 20, 2009): 814–20. http://dx.doi.org/10.1142/s0217979209060075.

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The effects of carbon and oxygen additions on the microstructure and mechanical properties of a new type low-cost beta titanium alloy Ti -4.3 Fe -7.1 Cr -3 Al have been studied. The results showed that with the carbon addition the grain size was refined significantly, followed by the tensile strength increase and ductility improvement. At 0.2 wt.% carbon addition the 0.2%YS increased by 22% and elongation increased to a peak value of 23%. Also with the carbon addition the oxygen content in the alloy could be allowed to reach 0.2wt.% without tensile property decrease. After ageing treatment, it was found that ageing temperature other than carbon content played a key role on the α-phase precipitation and ageing hardness. The hot-rolling deformation accelerated the ageing response. The optimal ageing process was decided to be 500°C for 1h under the pretreatment of 850°C hot-rolling followed by immediately water quenching. The reasons for these improvements were discussed in terms of the carbide pinning and α-phase precipitation.
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Samuel, Dayanand, Satish Babu Boppana, Kayaroganam Palanikumar, Ramesh S., and Virupaxi Auradi. "Role of Heat Treatment on Hardness of Al 6061- AlB2 Metal Matrix Composites." International Journal of Surface Engineering and Interdisciplinary Materials Science 9, no. 1 (January 2021): 26–39. http://dx.doi.org/10.4018/ijseims.2021010102.

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Insitu AlB2 particles with Al6061 combination system increase its hardness strength and abatement in density. Al6061-AlB2 insitu composites were created by exothermic response utilizing premixed halide salt KBF4 and Na3AlF6 (for refining aluminium matrix) by liquid strategy with distinct weight rates of AlB2 particles. The as cast matrix combination and the related insitu are exposed to heat treatment at a required temperature of 535°C for one hour followed by quenching in various media like ice, oil, and water. Then the specimens are exposed to an artificial ageing for 175°C for around 10 hours. Microstructural study was directed on as cast and insitu composite to determine the dissemination of AlB2 particles in the base matrix. The reinforced composite showed improvement in hardness when contrasted with as cast alloy. There has also been some improvement in hardness with increasing AlB2 content. The Al6061-AlB2 particulate composites showed critical improvement in hardness when quenched in ice.
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Alisibramulisi, A., Odd Geir Lademo, Ole Runar Myhr, and Per Kristian Larsen. "Mechanical Response of Aluminium Alloy AA6061 Butt-Welded Joints Subjected to Two Initial Tempers and Different Heat Treatments." Applied Mechanics and Materials 752-753 (April 2015): 51–54. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.51.

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Experimental studies have been carried out on butt-welded specimens of aluminium alloy AA6061. Two tempers; T4 and T6 prior to welding were investigated and the subsequent effects of natural ageing (NA) and post weld heat treatment (PWHT) were assessed. Digital image correlation (DIC) technique was used to obtain full field strain measurement on the transversely loaded tensile specimens. The tensile properties of these specimens are presented in terms of response curves. In addition, hardness profiles were also obtained. Both initial tempers and heat treatments were shown to give a significant effect on the mechanical response of the welded specimens tested.
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Bourgeois, Laure, Timothy Wong, X. Y. Xiong, Jian Feng Nie, and Barry C. Muddle. "Interaction between Cu and Sn in the Early Stages of Ageing of Al-1.7at.%Cu-0.01at.%Sn." Materials Science Forum 519-521 (July 2006): 495–500. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.495.

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The interaction between vacancies and Sn and Cu solute atoms in an Al-1.7at.%Cu- 0.01at.%Sn alloy was investigated by exploring the effect of incorporating natural ageing into conventional age hardening treatment. It was found that provided the artificial ageing temperature does not exceed a critical value between 160°C and 200°C, a narrow window of natural ageing (3-100 h) will result in a significant acceleration of the age hardening response and no decrease in peak hardness. Transmission electron microscopy showed that this effect reflects a large and rapid increase in number density of Cu GP(I) zones, and, to a lesser extent, of θ". The distribution and number density of θ' are essentially unaffected. Three-dimensional atom probe provided strong evidence that refinement of GP(I) zone distribution is not due to clustering of Cu atoms onto pre-existing Sn clusters. Instead it appears to be caused by a subtle interaction between vacancies, Sn and Cu atoms.
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Jarco, Aleksandra, and Jacek Pezda. "Effect of Heat Treatment Process and Optimization of Its Parameters on Mechanical Properties and Microstructure of the AlSi11(Fe) Alloy." Materials 14, no. 9 (May 4, 2021): 2391. http://dx.doi.org/10.3390/ma14092391.

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The paper presents the results of study concerning the evaluation of the precipitation hardening parameters (temperatures and times of solution treatment and artificial ageing processes) having an effect on mechanical properties, and the change in the microstructure of the EN AC-AlSi11(Fe) alloy. Based on the obtained results and performed statistical analysis, regression equations and the response surface model in the form of spatial and contour plots were determined to illustrate the effects of solution treatment and artificial ageing parameters on the mechanical properties of the investigated alloy. The performed heat treatment had a positive effect on improving the mechanical properties of the alloy versus the initial state. The maximum increase in tensile strength was by 52%, in unit elongation by 56%, in Brinell hardness by 44% and impact strength by 88%. Furthermore, a favorable change was observed in the microstructure of the investigated alloy, especially regarding eutectic silicon precipitations, which underwent partial spheroidization and coagulation after the heat treatment.
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29

Osuch, Piotr, Monika Walkowicz, Tadeusz Knych, and Stanislaw Dymek. "Impact of the Direct Ageing Procedure on the Age Hardening Response of Al-Mg-Si 6101 Alloy." Materials 11, no. 7 (July 19, 2018): 1239. http://dx.doi.org/10.3390/ma11071239.

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Al-Mg-Si alloys are used not only as construction material, but also as a material for electrical conductors. For this application, it is crucial for the alloy to achieve a balance between strength and electrical properties. This is achieved in practice by a combination of strain and precipitation hardening. The current paper focuses on a heat treatment procedure in which the EN AW 6101 alloy is cooled by a flowing air stream from the solutionizing temperature down to the artificial ageing temperature. The proposed procedure, unlike the common heat treatment leading to the T6 temper, allowed for the precipitation of the coarser β” phase with the presence of relatively wide precipitate-free zones. The age hardening response was investigated by Brinell hardness measurements, eddy current testing and microstructural observations using transmission electron microscopy (TEM). The applied heat treatment resulted in slightly lower strength (compared to the T6 temper), but improved electrical performance of the alloy.
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Mehta, Bharat, Lars Nyborg, Karin Frisk, and Eduard Hryha. "Al–Mn–Cr–Zr-based alloys tailored for powder bed fusion-laser beam process: Alloy design, printability, resulting microstructure and alloy properties." Journal of Materials Research 37, no. 6 (March 16, 2022): 1256–68. http://dx.doi.org/10.1557/s43578-022-00533-1.

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AbstractThis study introduces a family of unique Al–Mn–Cr–Zr-based aluminium alloys illustrated by two ternary and one quaternary variants. The choice of alloy compositions has created a system resistant to solidification cracking while retaining high amount of solutes in solid solution in as-printed condition. Good relative density (~ 99.5%) has been demonstrated along with microstructural study supported by X-ray diffraction to display solidification structure with nanometric precipitate formation in small amounts in as-printed condition. High levels of Mn and Cr produce significant solid solution strengthening reaching hardness of up to 102 HV in as-printed condition. Additionally, the combination of Mn, Cr and Zr is shown to be important to control precipitation strengthening upon direct ageing and coarsening resistance due to slow diffusivity. To elucidate the concept of precipitation strengthening, one set of alloys was aged at 678 K between 0 and 10 h and microhardness results showed that average hardness response reached 130 HV for the quarternary alloy. Graphical abstract
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31

Quan, Li Wei, Rui Wu, Da Ran Fang, Yuan Yuan Liu, and Chuan Cai Wang. "Effect of Pre-Treatment on the Precipitation Hardening of a Novel Al-Mg-Si Alloy." Advanced Materials Research 881-883 (January 2014): 1374–77. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1374.

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Al-Mg-Si alloy is used to investigate the bake-hardening response as automotive body panels. Natural aging followed by artificial aging at 170°C was carried on to study the effect of delaying at room temperature. Two methods are carried on to investigate the effect of pre-treatment on hardening response of Al-Mg-Si alloy. One is pre-aging in the range 80-140°Cfollowed by artificial aging at 170°C after natural aging for the same periods, and the other is retrogression treatment followed by artificial aging at 170°C after natural aging for the same periods. The properties of the alloy are tested by Vickers hardness measurements. And it is found that the optimal pre-ageing is 170°C for 30min and the opimal retrogression treatment is 230°C for 15s.
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32

Fujda, Martin, Miloš Matvija, and Miroslav Glogovský. "Effect of Natural Aging on Mechanical Response of the Artificially Aged EN AW 6063 Aluminium Alloy." Materials Science Forum 952 (April 2019): 74–81. http://dx.doi.org/10.4028/www.scientific.net/msf.952.74.

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The effect of natural pre-aging time (from 0.1 to 10000 h) on mechanical response during subsequent artificial aging of EN AW 6063 aluminium alloy at 170°C was investigated using Vickers microhardness measurements, tensile test analysis and transmission electron microscopy characterization. The microhardness and tensile strength of EN AW 6063 alloy increased slightly with natural aging time. Afterward, the artificial ageing from 18 to 20 hours induced the maximum increasing of hardness and strength for variously naturally pre-aged states of alloy. But, it was found that when pre-aging time was prolonged from 0.1 h to 10000 h, the mechanical response of artificial aging applied for the pre-aged alloy states was slightly improved. It was suggested, that as pre-aging time was increased, the size of β'-phase particles formed in solid solution of pre-aged alloy state during artificial aging was decreased and their amount was increased.
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33

Al-Salihi, Huda, Colleen J. Bettles, and Barry C. Muddle. "The Ageing Behavior of Titanium Alloy Ti-10V-2Fe-3Al." Materials Science Forum 654-656 (June 2010): 843–46. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.843.

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A good combination of high strength and hardenability makes the alloy Ti 10V-2Fe-3Al a prime candidate for applications in the aerospace arena. However, these properties are very dependent on a post-forming heat treatment. The overall objective of this work is to determine the effect of prior deformation on the aging behaviour. In this particular study, the influence of the heat treatment, either solution and/or aging, on the microstructures, and consequently on the mechanical properties, without introduced strain is reported. Various solution heat treatments have been conducted, either in the β phase or in the (α+β) phase field, followed by rapid quenching or slow cooling, and aging treatments at different temperatures (250, 350, 400, 500C°) above and below the ω-transus temperature. Vickers hardness indentations were used to follow the precipitation hardening behaviour, and mechanical properties were determined using a shear punch test. The aging response is dependent not only on the presence of the athermal ω phase but also on the proximity of the aging temperature to the ω-transus. Most treatments showed an unusual initial softening behaviour prior to age hardening, however this appears to be related again to the composition and fraction of the β phase retained after solution treatment.
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34

Sofyan, Bondan Tiara, Immalatul Husna, and Muhammad Syahid. "Effects of Cu Addition on the Precipitation Process of Al-9Zn-4Mg-xCu (wt. %) Alloys at 130°C." Applied Mechanics and Materials 835 (May 2016): 222–29. http://dx.doi.org/10.4028/www.scientific.net/amm.835.222.

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Aluminium is a light-weight material and possesses high corrosion resistance, so that it is widely used in manufacturing industries. The Al-Zn series have the highest strength compared to other aluminium alloys. To further increase the strength of Al-Zn alloys, Mg and Cu are added and age hardening treatment is applied. This research studied the precipitation process in Al-9Zn-4Mg (wt. %) alloys with Cu content of 0, 1, 3 and 5 wt.%. The alloys were produced through investment casting taking the shape of turbine impeller. The samples were solution treated at 460 °C for 2 hours and then aged at 130 °C. The characterization included hardness testing to observe response of age hardening, microstructural observation and Differential Scanning Calorimetry (DSC) testing. Microstructural observation was conducted by optical microscope and Scanning Electron Microscope (SEM) which was combined with Energy Dispersive Spectroscopy (EDS). The results showed that addition of Cu initially decreased the hardness during early ageing (2 hours) due to segregation of Cu-V complexes toward the grain boundaries which then decreased the hardness and enlarged the grain boundary phases. However, the peak hardness of the alloys was not affected by the increase in Cu content. due to high concentration of Zn and Mg. Exothermic reactions of formation of GP zones, η", η' and η (MgZn2) were found during precipitation process while endothermic reaction were observed due to dissolution of the phases. Presence of MgZn2 and Al7Cu2Fe second phases were observed in grain boundaries.
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35

Tezcan, R., and H. Jones. "The effect of alloy composition on the hardness and ageing response of rapidly solidified Al-Cr-Zr-Mn alloy powder particulate." Materials Letters 10, no. 6 (December 1990): 231–34. http://dx.doi.org/10.1016/0167-577x(90)90023-f.

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36

Feijoo, Iria, Pedro Merino, Gloria Pena, Pilar Rey, and Marta Cabeza. "Microstructure and Mechanical Properties of an Extruded 6005A Al Alloy Composite Reinforced with TiC Nanosized Particles and Strengthened by Precipitation Hardening." Metals 10, no. 8 (August 4, 2020): 1050. http://dx.doi.org/10.3390/met10081050.

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High-energy ball milling was carried out to disperse 3 vol% TiC nanoparticles (ex situ reinforcement) in a high-pressure inert gas-atomised prealloyed micron-sized 6005A Al alloy (AA6005A), with a Si/Mg atomic ratio of 1.32 powder matrix. Nanocomposite powders were consolidated by hot extrusion in strip shape at 500 °C, followed by a T6 ageing heat treatment. The microstructural features of the consolidated and precipitation hardening nanocomposites specimens were studied using X-ray diffractometry (DRX), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). The consolidated nanocomposites consisted of approximately equiaxed grains of different grain sizes with a high fraction of high-angle grain boundaries with average misorientation angles of approximately 35°. The nanocomposites showed remarkably higher hardness, Young’s modulus, yield, and ultimate strengths at room temperature than the extruded profiles of unreinforced milled AA6005A powders obtained through refinement of the Al alloy grain structure and a strong particle–matrix bonding, although with a drop in their ductility. The consolidated nanocomposite showed a weak response to industrial ageing heat treatment, as demonstrated by microstructural analyses and mechanical tests.
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37

Vidakis, Nectarios, Markos Petousis, Athena Maniadi, Emmanuel Koudoumas, Achilles Vairis, and John Kechagias. "Sustainable Additive Manufacturing: Mechanical Response of Acrylonitrile-Butadiene-Styrene over Multiple Recycling Processes." Sustainability 12, no. 9 (April 27, 2020): 3568. http://dx.doi.org/10.3390/su12093568.

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Sustainability in additive manufacturing refers mainly to the recycling rate of polymers and composites used in fused filament fabrication (FFF), which nowadays are rapidly increasing in volume and value. Recycling of such materials is mostly a thermomechanical process that modifies their overall mechanical behavior. The present research work focuses on the acrylonitrile-butadiene-styrene (ABS) polymer, which is the second most popular material used in FFF-3D printing. In order to investigate the effect of the recycling courses on the mechanical response of the ABS polymer, an experimental simulation of the recycling process that isolates the thermomechanical treatment from other parameters (i.e., contamination, ageing, etc.) has been performed. To quantify the effect of repeated recycling processes on the mechanic response of the ABS polymer, a wide variety of mechanical tests were conducted on FFF-printed specimens. Regarding this, standard tensile, compression, flexion, impact and micro-hardness tests were performed per recycle repetition. The findings prove that the mechanical response of the recycled ABS polymer is generally improved over the recycling repetitions for a certain number of repetitions. An optimum overall mechanical behavior is found between the third and the fifth repetition, indicating a significant positive impact of the ABS polymer recycling, besides the environmental one.
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38

Zupanič, Franc, and Tonica Bončina. "Heat-Resistant Al-Alloys with Quasicrystalline and L1<sub>2</sub>- Precipitates." Solid State Phenomena 327 (January 10, 2022): 26–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.327.26.

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We have been developing Al-Mn-Cu based alloys alloyed with minor additions of different elements. Small additions of beryllium enhance the formation of the icosahedral quasicrystalline phase (IQC) during solidification, especially during ageing. Upon solidification, primary IQC-particles may form, with sizes, ranging from 5 to 50 μm. IQC is also present as a part of binary eutectic in the interdendritic regions. More importantly, nanosized quasicrystalline precipitates can form during T5-treatment at temperatures ranging from about 250−450 °C. They are, in fact, metastable precipitates transforming to ternary T-precipitates (Al20Mn3Cu2) phase above 450 °C. The heat resistance can be increased considerably by the addition of Sc and Zr by forming L12-precipitates in spaces between quasicrystalline precipitates. In this paper, we studied three alloys, two Al-Mn-Cu-Be alloys and an Al-Mn-Cu-Be-Sc-Zr alloy. The alloys were produced by vacuum induction melting and casting into a copper mould. We investigated the response of the alloys to different heat treatments and their heat resistance at higher temperatures. It was shown that the alloys could be precipitation strengthened by ageing at 300 °C and 400 °C. The hardness of the alloy stayed at relatively high levels even at 500 °C, while more substantial softening occurred at 600 °C.
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39

García-Moreno, Irene, Miguel Caminero, Gloria Rodríguez, and Juan López-Cela. "Effect of Thermal Ageing on the Impact Damage Resistance and Tolerance of Carbon-Fibre-Reinforced Epoxy Laminates." Polymers 11, no. 1 (January 17, 2019): 160. http://dx.doi.org/10.3390/polym11010160.

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Composite structures are particularly vulnerable to impact, which drastically reduces their residual strength, in particular, at high temperatures. The glass-transition temperature (Tg) of a polymer is a critical factor that can modify the mechanical properties of the material, affecting its density, hardness and rigidity. In this work, the influence of thermal ageing on the low-velocity impact resistance and tolerance of composites is investigated by means of compression after impact (CAI) tests. Carbon-fibre-reinforced polymer (CFRP) laminates with a Tg of 195 °C were manufactured and subjected to thermal ageing treatments at 190 and 210 °C for 10 and 20 days. Drop-weight impact tests were carried out to determine the impact response of the different composite laminates. Compression after impact tests were performed in a non-standard CAI device in order to obtain the compression residual strength. Ultrasonic C-scanning of impacted samples were examined to assess the failure mechanisms of the different configurations as a function of temperature. It was observed that damage tolerance decreases as temperature increases. Nevertheless, a post-curing process was found at temperatures below the Tg that enhances the adhesion between matrix and fibres and improves the impact resistance. Finally, the results obtained demonstrate that temperature can cause significant changes to the impact behaviour of composites and must be taken to account when designing for structural applications.
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40

Shoummo, Mashiur Rahman, Akib Abdullah Khan, and Mohammad Salim Kaiser. "True Stress-Strain Behavior of Al-based Cast Automotive Alloy Under Different Ageing Conditions and the Effect of Trace Zr." Journal of Mechanical Engineering Science and Technology (JMEST) 6, no. 2 (November 15, 2022): 95. http://dx.doi.org/10.17977/um016v6i22022p095.

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A thorough investigation has been carried out on the Al-12Si-1Mg-1Cu-1Ni automotive alloy considering different properties, specially mechanical properties associated with true stress and true strain with Zr addition of trace amount. A commercially available piston is melted to produce the alloy, and trace amount of Zr is added to make another. The base alloy along with the Zr added alloy had been applied to homogenization, solution treatment, quenching, and ageing in order to get the age-hardening response. The alloys have been heat-treated at 25 ºC, 200 ºC, and 300 ºC, respectively, for four hours for attaining the under, peak and over-aged states, respectively. During ageing, Al2Cu and Mg2Si phases are formed in the aluminium matrix leading to peak-aged strength, which is reduced at over-aged state because of coarsening of precipitation and recrystallizing, shown by the tensile and hardness properties. When Zr is added to the alloy, Al3Zr phases appear while casting and heat-treatment, resisting the drop of strength at over-aged state. It is visible in the stress-strain diagram that at over-aged conditions, the alloy with trace Zr shows improved strength and ductility. In the micrographs of Zr added alloy, finer distributed grains are visible through the grain refinement of Zr, which also prevents recrystallization at over-aged conditions. The homogeneity of the grains as a result of the Zr addition's microstructural change was further confirmed by fractography. It is clear that adding Zr to such alloys does not greatly increase their strength, but it does restrict the declining of strength by preventing the production of thermally stable Al3Zr precipitates, which coarsens the resisting behavior of various intermetallics in the thermally damaged alloy.
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41

Zhang, Qun Li, Saksham Dhawan, Xi Luan, Qiang Du, Jun Liu, and Li Liang Wang. "Investigation and Constitutive Modelling of High Strength 6xxx Series Aluminium Alloy: Precipitation Hardening Responses to FAST (Fast Light Alloys Stamping Technology) and Artificial Ageing." Materials Science Forum 941 (December 2018): 814–20. http://dx.doi.org/10.4028/www.scientific.net/msf.941.814.

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FAST (Fast light Alloys Stamping Technology) has recently been developed to efficiently and economically manufacture lightweight, high strength structural components from aluminium alloys sheet. Post-form strength prediction of 6xxx series aluminium alloy (AA6xxx) after FAST and multiple stage heat treatments has been a challenge. This is due to the effect of pre-existing dislocations induced via high temperature plastic deformation in the forming process. In the present research, a new PFS (post-form strength) model has been proposed to predict the age-hardening response of AA6xxx alloys undergoing FAST and subsequent thermal cycles. The model incorporates two sub-models, for simulating viscoplastic flow and predicting strength evolution respectively. The first sub-model incorporates a set of constitutive equations, developed to model the stress-strain curve of AA6xxx during FAST. The second sub-model employs precipitation-hardening and dislocation-hardening theories to simulate the evolution of microstructure and, as a consequence, strength of alloys undergoing artificial ageing cycles. This is calculated by considering the intrinsic resistance of the alloy to dislocation movement due to solute atoms and precipitates. The strength was computed accurately via the internal state variables method, in which dislocation density, volume fraction of precipitates, solute concentration and radii of precipitates were correlated. Furthermore, the model was validated by comparing results with transmission electron microscope (TEM) images as well as hardness measurements. Hence, the model performs as a powerful and comprehensive tool to simulate post-form strength of 6xxx series aluminium alloys that undergo complicated thermomechanical processes including high temperature deformation and post-form heat treatment, with less than 5% deviation between measured and predicted values.
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42

Wu, Xin Hua, Joaquin Del Prado, D. Hu, A. Huang, M. Q. Chu, and M. H. Loretto. "Ageing of C-Containing and C-Free Ti-15Cr and Ti-15-3." Materials Science Forum 539-543 (March 2007): 3595–600. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3595.

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Samples of Ti-15Cr and Ti-15V-3Sn-3Al-3Cr (wt%) containing controlled additions of carbon up to 0.2wt% and different oxygen contents have been quenched and aged at temperatures between 400 and 600°C. Optical, scanning and analytical transmission electron microscopy have been used to characterise the microstructures of the quenched and aged samples. Hardness testing has been used to follow the kinetics and extent of age hardening, which are accelerated in Ccontaining samples. The addition of carbon results in the formation of Ti(CxOy) precipitates which pin grain boundaries in forged samples so that the grain size in the quenched C-containing samples is about a factor of ten less than that in the C-free samples. In the C-free samples coarse grain boundary alpha tends to form, but in the C-containing samples alpha precipitation is more uniform throughout the beta grains. The extent of omega precipitation is very different in the two alloys; the Ti-15Cr alloy forms athermal omega in the as-quenched samples and large omega precipitates are formed on ageing at 400°C. No evidence for omega has been obtained in the Ti-15-3. The hardening responses and microstructural observations are interpreted in terms of the different grain boundary oxygen contents in the C-containing and C-free samples and the different roles of omega and of carbon in the two alloys.
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43

"Optimization of Age Hardening Behaviour of AA2024 Hybrid Composite Reinforced with Red Mud and Fly Ash through RSM." International Journal of Engineering and Advanced Technology 9, no. 1 (October 30, 2019): 762–70. http://dx.doi.org/10.35940/ijeat.a1367.109119.

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Hybrid AA2024 Metal Matrix composite find explicit application, so important factors like Hardness, lightweight is considered and hybrid composite was synthesized by stir casting route. In this investigation, the effects of age hardening on Hardness of AA2024 reinforced with industrial wastes is measured by using a Vickers hardness test and the influence of different process parameters are studied using Design Expert. A Response Surface Methodology is an effective technique used to observe the impact of age hardening parameters and their interconnection on surface hardness of the prepared hybrid AA2024 composite. A mathematical model was created to optimize the weight percentage of reinforcement and artificial ageing process parameters for maximum Hardness. Adequacy and lack of fit of the developed model were checked using the Analysis of variance Technique. Hardness is taken as the response and optimum parameters are obtained by using the quadratic model. Based on the results, it can be perceived that the weight percentage of Red mud, ageing temperature and ageing time has shown a notable effect on the response. For a specifically optimized parameter, the hardness is improved and it was observed that ageing temperature is the most influencing factor based on the RSM. The optimized parameters for the desired response are Ageing Temperature is 198.87ᵒC, Ageing time is 6.82884 hours, and Red mud wt % is 4.2865 respectively. A confirmation test is carried out with the optimized parameters experimentally and its error is less than the 5 % which shows good results with RSM. Surface morphological studies are carried for the optimized Age Hardened hybrid composite and it showed the uniform distribution of reinforcements in the matrix. Because of the increased hardness, these hybrid composite would perceive real time applications like Orthopaedic braces, aircraft structures and manufacturing crew machine products.
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44

Gharbi, Oumaïma, Shravan Kumar Kairy, Paula Roberta De Lima, Derui Jiang, Juan Nicklaus, and Nick Birbilis. "Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing." npj Materials Degradation 3, no. 1 (November 27, 2019). http://dx.doi.org/10.1038/s41529-019-0101-6.

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AbstractAdditively manufactured high strength aluminium (Al) alloy AA7075 was prepared using selective laser melting (SLM). High strength Al-alloys prepared by SLM have not been widely studied to date. The evolution of microstructure and hardness, with the attendant corrosion, were investigated. Additively manufactured AA7075 was investigated both in the “as-produced” condition and as a function of artificial ageing. The microstructure of specimens prepared was studied using electron microscopy. Production of AA7075 by SLM generated a unique microstructure, which was altered by solutionising and further altered by artificial ageing—resulting in microstructures distinctive to that of wrought AA7075-T6. The electrochemical response of additively manufactured AA7075 was dependent on processing history, and unique to wrought AA7075-T6, whereby dissolution rates were generally lower for additively manufactured AA7075. Furthermore, immersion exposure testing followed by microscopy, indicated different corrosion morphology for additively manufactured AA7075, whereby resultant pit size was notably smaller, in contrast to wrought AA7075-T6.
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