Academic literature on the topic 'Cu-based alloy'

Anticipating an alloy's corrosion resistance is essential to avoid product failure and reduce costs. Research and analyze the corrosion resistance of Al-Cu, Al-Zn and Al-Cu-Zn alloys based on the analytical balance of the elements according to weight, thermodynamic, metallurgical rules on metal alloys, kinetic and other properties. The purpose of this study is to determine the corrosion resistance of Al-5-wt% Cu, Al-5-wt% Zn and Al-5-wt% Cu-5-wt% Zn alloys based on the analytical calculation. Based on the analytical calculation results, the Al-Zn-Cu alloy has the best corrosion resistance with a corrosion rate of 0.4375 mmpy. Next is the Al-Cu alloy with a corrosion rate of 0.4634 mmpy. While Al-Zn alloy has the lowest strength with a corrosion rate of 0.4828 mmpy. Based on standard EMF potential values for these three alloys. Al-Zn alloys are most active with an value of-1.61 V, followed by Al-Zn-Cu alloys with an value of - 1.60 V, and the noblest Al-Cu alloy has the most positive value of-1.56 V. Faraday's law to get corrosion rates of the anode and cathode materials. In the third reaction, the exothermic alloy has a positive value of so the exothermic reaction occurs.

A comparative study on the friction and wear properties of three kinds of copper alloys, including Cu-Ni based, Cu-Al and Cu-Be alloys was carried out in this study. The friction pair was stainless steel, and both dry and MoS2 lubrication friction experiments were investigated. During the experiments, different loads were chosen for different alloys. It was found that under dry friction condition, the friction coefficients of both Cu-Ni based and Cu-Al alloys did not change as the loads changes, whereas the friction coefficient of Cu-Be alloy increased as the loads increases. Under lubrication friction condition, the friction coefficients of all three alloys did not change as the load changes. The results show that the dry friction coefficient of Cu-Ni based alloy was the largest (0.74), the Cu-Al alloy next (0.60), and the Cu-Be alloy had the smallest dry friction coefficient (0.54). The lubrication friction coefficient of Cu-Ni based and Cu-Be was equal and relatively smaller (0.12), whereas the Cu-Al alloy had a relative larger lubrication friction coefficient (0.27). The microstructure observations were consistent with the friction and wear performance, and the SEM results show that different wear mechanisms were dominated for different alloys.

High-strength Cu-based bulk glassy alloys with a large supercooled liquid region in Cu-Zr-Ti-Ni systems were prepared by means of copper mold casting. The Cu-based bulk glassy alloys samples were tested by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Instron testing machine. The result indicates, the maximum diameter was 5.0 mm for the Cu55Zr25Ti15Ni5 bulk glassy alloy. The temperature interval of supercooled liquid region (ΔTx) is as large as 45.48-70.98 K for the Cu-Zr-Ti-Ni alloy. The Cu-based glassy alloys rods exhibited the very high mechanical properties and the distinct plastic strains. The compressive fracture strength is 2155 MPa, 2026 MPa and 1904 MPa respectively for Cu50Zr25Ti15Ni10, Cu55Zr25Ti15Ni5 and Cu54Zr22Ti18Ni6 bulk glassy alloys. The Vickers hardness is respectively 674, 678 and 685 for the Cu50Zr25Ti15Ni10, Cu55Zr25Ti15Ni5 and Cu54Zr22Ti18Ni6 bulk glassy alloys. The addition Co element to Cu-Zr-Ti-Ni alloy expand the ΔTx, the ΔTx is 74.5 K for Cu50Zr22Ti18Ni6Co4 bulk glassy alloys.

The Cu-based bulk glassy alloys in Cu-Zr-Ti-Ni systems were prepared by means of copper mold casting. The structure and corrosion resistance of Cu-based bulk glassy alloys were analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), electrochemistry method, lost weight method. The result indicates the supercooled liquid temperature interval (ΔTx) is up to 70.98 K for Cu50Zr25Ti15Ni10bulk glassy alloy. The maximum diameter was up to 5.0 mm for the Cu55Zr25Ti15Ni5bulk glassy alloy. For electrochemistry corrosion in 3.5% NaCl solution, self-corrosion electric current density of the Cu50Zr25Ti15Ni10bulk glassy alloys is obviously lower than that of stainless steel and brass, so corrosion resistance of Cu-based bulk glassy alloys is better than stainless steel and brass at the same corrosion condition. The lost weight method showed that the corrosion rate of brass, stainless steel and glassy alloy is respectively 10.08 g/(m2•h), 6.08 g/(m2•h) and 2.19 g/(m2•h) in the 3% NaCl solution, which also indicates that the corrosion resistance of Cu-based bulk glassy alloys is better than stainless steel and brass. The Cu-based bulk glassy alloys can be used in the special field demanding to have the super high strength, hardness and corrosion resistance.

The Al-5wt.%Cu based alloy with different levels of Al5Ti1B master alloy additions have been prepared by conventional casting method. The effect of Al5Ti1B contents on microstructure of Al-Cu based alloy was studied by means of XRD, OM and SEM. The results show that when the addition level of Al5Ti1B master alloy is less than 0.6wt.%, the average grain size of the alloys decreases with the increase of Al5Ti1B content. But the grain size increases somewhat with further addition of Al5Ti1B. It is considered that TiB2 particles can serve as the heterogeneous nucleation sites of α-Al during solidification, and heterogeneous nucleation is the main reason of the grain refinement of Al-Cu based alloy. The superior comprehensive mechanical properties of tensile strength of 435 MPa and elongation of 11% of the refined Al-5wt.%Cu based alloy with 0.6% Al5Ti1B were obtained after solution and aging treatment.

There is a great attention to the usage rate of Al-Cu alloys due to the largely use of Al-5%Cu based alloys in the aerospace industry in the past decades. The improvement of microstructure and properties of Al-5%Cu based alloy by refinement and modification. Specially, the refinement and modification of Al-Cu alloy can be achieved by addition of rare earth. In this paper, the effect of Y on the microstructure and properties of Al-5%Cu based alloy was investigated. The results show that θ (Al2Cu) phases change from mesh structure into fish-bone shape and grains are refined. Y additions promoted the end-solidification temperature and decreased the quantity of eutectic in grain boundaries, and narrowed the crystallization range and increased the hot-tearing resistance and decreased the hot-tearing susceptibility significantly.

Cu–Cr-based alloys exhibit excellent electrical conductivity and strength, but their poor thermal stability limits their application in industry. In this paper, Cu–0.2Cr (at. %) and Cu–0.2Cr–0.12Ag (at. %) alloys were prepared to study the effect of Ag on the properties, microstructure, and thermal stability of the Cu–Cr alloy. Microstructure and precipitation were observed by an optical microscope (OM) and a transmission–electron microscope (TEM). After cold-drawing by 99.9% and aging at 450 °C for 2 h, the peak hardness and electric conductivity of the Cu–Cr alloy were 120.3 HV and 99.5% IACS, respectively, and those of the Cu–Cr–Ag alloy were 135.8 HV and 98.3% IACS, respectively. The softening temperature of the Cu–Cr alloy was 500~525 °C, and that of the Cu–Cr–Ag alloy was about 550 °C. The creep strains of the Cu–Cr and Cu–Cr–Ag alloys at 40 MPa and 400 ℃ for 50 h were 0.18% and 0.05%, respectively. Ag elements improved the thermal stability of the Cu–Cr alloy. Recovery and recrystallization occurred before the coarsening of precipitates during the softening process. Ag atoms mainly improved the softening resistance of the alloy by delaying recrystallization, and mainly increased creep resistance by preventing the increase in mobile-dislocation density.

Corrosion of a multi-phase Ag-Pd-Cu-Au-based commercial dental casting alloy and a Cu-Pd-rich and Ag-rich single-phase alloy was studied by open-circuit potential measurements, atomic absorption spectrometry, and electron spectroscopy. The alloys were immersed in an artificial saliva solution for 24 hr while the open-circuit potentials of the alloys were measured. The potentials were found to stabilize at certain levels after a steep rise during the first hours of the experiment. Cu was found to dissolve considerably from the Cu-Pd-rich alloy, with simultaneous enrichment of Pd in the surface layer of the alloy. Ag dissolved slightly from the Ag-rich alloy, but both Cu and Ag were found to dissolve from the multi-phase alloy. Neither Pd nor Au dissolved from any of the alloys studied.

We have focused on shape-memory properties of Cu-Sn based ternary alloys in this study. We have attempted to suppress degradation at room temperature aging and to improve the amount of shape recovery by adding the third element to a binary Cu-Sn alloy. The attempt has successfully conducted in Cu-Sn-Mn alloy, the degradation due to aging at room temperature was suppressed and the thermal stability was improved. Furthermore, the present study revealed that Cu-Sn-Mn alloy exhibited a large super elastic recovery in three point bending tests. We have also investigated the shape-memory properties of Cu-Sn-Si alloys and revealed that the ternary alloy has achieved super-elastic recovery better than the Cu-Sn-Mn alloy in the three-point bending tests.

The formation, structure and properties of bulk copper-based alloy glasses have been studied systematically. The production techniques employed included chill block melt produced as" cylindrical rods by casting into a stepped copper die having internal diameters raging between 0.5 and 4 mm and as conical bulk shapes, with a length of 50 mm and cone base diameters in the range 2-10 mm.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 39-40).
The Taylor method is a proven way to produce Cu-based shape memory microwires that aren't plagued by problems typical in polycrystalline copper SMAs produced by other methods. Here we set out to expand and refine this processing method to take the first critical steps toward large-scale continuous production. Using a semi-automated processing route, we draw continuous, uniform fibers up to 5 meters in length with diameters in the range 10 - 35 microns. Particular attention is paid to microwires made from a Cu-Sn shape memory alloy. In addition, because the properties of shape memory microwires depend on their diameter, processing parameters were varied to understand their impact on the diameters of the resulting wires.
by Eric Szablinski.
S.M.

The aim of this study is to synthesize and characterize new bulk amorphous alloys in the Ni- based systems. Theoretical studies on the basis of semi-empirical rules and the electronic theory of alloys in pseudopotential approximation has been provided in order to predict the impurity elements that will lead to an increase in the glass forming ability of Ni-based alloy systems. Glass forming ability of ten different compositions of alloys of Ni-Nb, Ni-Fe, Ni-B, Ni-Hf and Ni-Cr was simulated by using FORTRAN programs based on pseudopotential theory. In addition to the binary alloys, ternary alloys, which were formed by addition of 1 at% of third element to these systems, were also simulated. Since ordering energy is an indicator of glass forming ability, theoretical studies allowed to predict the effect of various third elements on the formation of amorphous phase. Furthermore, ordering energies were also used to calculate other parameters important for glass forming ability. In the second part of the study, on the basis of theoretical results, a series of casting experiments were done. Different compositions of Ni-Nb, Ni-Nb-Sn and Ni-Nb-Al alloys were cast in the centrifugal casting machine. Alloys were melted in alumina crucibles and cast into the copper moulds. Characterizations of cast alloys were done by the use of Metallography, SEM, XRD and DSC. Fully amorphous Ni52Nb41Al7 alloy was synthesized in bulk form with 0.8 mm thickness.

La conception des ouvrages économiques a suscité de nombreux progrès dans les domaines de la modélisation et de l’optimisation, permettant l’analyse de structures de plus en plus complexes. Cependant, les conceptions optimisées sans considérer les incertitudes des paramètres, peuvent ne pas respecter certains critères de fiabilité. Pour assurer le bon fonctionnement de la structure, il est important de prendre en considération l’incertitude dès la phase de conception. Il existe plusieurs théories dans la littérature pour traiter les incertitudes. La théorie de la fiabilité des structures consiste à définir la probabilité de défaillance d’une structure par la probabilité que les conditions de bon fonctionnement ne soient pas respectées. On appelle cette étude l’analyse de la fiabilité. L’intégration de l’analyse de fiabilité dans les problèmes d’optimisation constitue une nouvelle discipline introduisant des critères de fiabilité dans la recherche de la configuration optimale des structures, c’est le domaine de l’optimisation fiabiliste (RBDO). Cette méthodologie de RBDO vise donc à considérer la propagation des incertitudes dans les performances mécaniques en s’appuyant sur une modélisation probabiliste des fluctuations des paramètres d’entrée. Dans ce cadre, ce travail de thèse porte sur l’analyse robuste et l’optimisation fiabiliste des problèmes mécaniques complexes. Il est important de tenir compte des paramètres incertains du système pour assurer une conception robuste. L’objectif de la méthode RBDO est de concevoir une structure afin d’établir un bon compromis entre le coût et l’assurance de fiabilité. Par conséquent, plusieurs méthodes, telles que la méthode hybride et la méthode optimum safety factor, ont été développées pour atteindre cet objectif. Pour remédier à la complexité des problèmes mécaniques complexes comportant des paramètres incertains, des méthodologies spécifiques à cette problématique, tel que les méthodes de méta-modélisation, ont été développées afin de bâtir un modèle de substitution mécanique, qui satisfait en même temps l’efficacité et la précision du modèle
The design of economic system leads to many advances in the fields of modeling and optimization, allowing the analysis of structures more and more complex. However, optimized designs can suffer from uncertain parameters that may not meet certain reliability criteria. To ensure the proper functioning of the structure, it is important to consider uncertainty study is called the reliability analysis. The integration of reliability analysis in optimization problems is a new discipline introducing reliability criteria in the search for the optimal configuration of structures, this is the domain of reliability optimization (RBDO). This RBDO methodology aims to consider the propagation of uncertainties in the mechanical performance by relying on a probabilistic modeling of input parameter fluctuations. In this context, this thesis focuses on a robust analysis and a reliability optimization of complex mechanical problems. It is important to consider the uncertain parameters of the system to ensure a robust design. The objective of the RBDO method is to design a structure in order to establish a good compromise between the cost and the reliability assurance. As a result, several methods, such as the hybrid method and the optimum safety factor method, have been developed to achieve this goal. To address the complexity of complex mechanical problems with uncertain parameters, methodologies specific to this issue, such as meta-modeling methods, have been developed to build a mechanical substitution model, which at the same time satisfies the efficiency and the precision of the model

Cu-based alloys are widely applied in corrosive environments. The improvement of the alloys' corrosion resistance will significantly reduce energy consumption and overexploitation of resources. To increase the resistance of copper as less corrosion resistant alloy component, nine imidazole-based compounds with different functional groups were tested as potential corrosion inhibitors. Imidazole derivatives were chosen as a potential inhibitor for copper alloys due to its diverse performance on pure Cu. Besides, CuZn alloys, CuZr crystalline and amorphous alloys, and their pure metals were tested to explore the correlations between inhibition, structure and atomic species. The determination of the performance of corrosion inhibitors on metals is a complex problem due to the mixed influence of surface condition, inhibitor-surface interaction and environmental conditions. For CuZn alloys, the a-Cu phase Cu70Zn30 alloy and non-a-Cu phase Cu30Zn70 alloy were tested. CuZr alloys are the basis of a family of metallic glasses with large glass forming ability and remarkable mechanical properties. The corrosion response of as-produced crystalline and amorphous CuxZr(100-x )alloys (x = 40, 50, 64 at. %) was tested. All alloys were immersed in 3 wt.% NaCl aqueous solution without and with 1mM inhibitor concentration. Potentiodynamic polarization measurements, electrochemical impedance spectroscopy and long-term immersion tests followed by microscopy analysis and Raman spectroscopic analysis were carried out. Comparative analysis of pure Cu and Cu70Zn30 alloy shows that the same inhibitors are effective in both alloys. A similar behavior is found with pure Zn and Cu30Zn70 alloy. However, the inhibition power shows a different value, which should be attributed to the healing effect. Defects present in most of the polished samples accelerate the pitting on these locations. The healing effect will lead to a patch on those positions, which will slow down the local attacks. All the tested CuZr amorphous alloys exhibit a much better corrosion resistance than their crystalline counterparts in the presence and absence of inhibitors. The main factor controlling the corrosion resistance of the alloys appears to be the Zr-rich (or at least equiatomic) amorphous structure, the effect of the inhibitors being secondary. Results therefore show a complex relationship between inhibitor performance, microstructure and composition of CuZr alloys. SH-ImiH-4Ph shows potential to become a global a-Cu phase alloy inhibitor and SH-BimH-5NH2 shows potential for Zn-based and CuZr alloys. Electrochemical measurements, especially long-term measurements, display a significant correlation to immersion tests. The conducted research offers some understanding on the corrosion mechanism and resistance after inhibitor application. Previous surface oxidation, defects on the surface, and inhibitor functional group are found to be the most significant factors that influence inhibition. The healing effect is also responsible for the improved efficiency of some inhibitors.
Els aliatges de coure es fan servir freqüentment en entorns corrosius. La millora de la resistència a la corrosió reduiria notablement el consum d’energia i la sobreexplotació de recursos naturals. Nou derivats de l’imidazol amb diferents grups funcionals ha estat analitzats com a potencials inhibidors de la corrosió, per tal d’augmentar la resistència a la corrosió del Cu. S’escolliren derivats de l’imidazol a la vista de la seva resposta diferent com a inhibidors de la corrosió en Cu pur. Aquest inhibidors han estat aplicats sobre els metalls purs i sobre aliatges CuZn i CuZr cristal·lines i amorfes, per tal d’explorar les correlacions entre inhibició, estructura i espècies atòmiques. La determinació de l’eficiència d’inhibició en metalls és un problema complex a causa de la influència creuada entre les condicions a la superfície, la interacció inhibidor-superfície i les condicions ambientals. En aliatges CuZn s'han estudiat les composicions Cu70Zn30 (fase a-Cu) i Cu30Zn70 (fase no-a-Cu). Els aliatges CuZr són la base d'una família de vidres metàl·lics amb gran capacitat d’amortització i excel·lents propietats mecàniques. S'ha determinat la resistència a la corrosió d'aliatges cristal·lins i amorfs de composició CuxZr (100-x) (x = 40, 50, 64 at.%). Tots els aliatges van ser analitzades en dissolució aquosa contenint un 3% de NaCl en pes, sense i amb una concentració de 1mM de l'inhibidor. S'han efectuat mesures dinàmiques de polarització, espectroscòpia d'impedància electroquímica i immersió durant períodes prolongats seguida de microscòpia i espectroscòpia Raman. L'anàlisi comparativa mostra que els inhibidors efectius en Cu pur ho són també en Cu70Zn30. Un comportament similar apareix entre Zn i Cu30Zn70. No obstant això, el poder d'inhibició mostra un valor molt diferent, que s'atribueix a l'efecte de "cicatrització". Els defectes presents en la majoria de les mostres acceleren la corrosió localitzada (pitting) en aquests punts. L'efecte de cicatrització produeix "pegats" en les mateixes posicions, el que redueix la velocitat de l'atac localment. Els aliatges CuZr cristal·lins mostren una resistència a la corrosió molt més alta que els aliatges cristal·lins amb la mateixa composició, originalment i en presència d'inhibidors. El principal factor que controla la resistència a la corrosió dels aliatges és l'alta concentració de Zr (al menys equiatòmica) en l'estructura amorfa; l'efecte dels inhibidors resulta ser secundari. Els resultats mostren una relació complexa entre l'eficiència de l'inhibidor, la microestructura i la composició dels aliatges CuZr. SH-ImiH-4Ph mostra potencial per inhibir la corrosió en aliatges on la fase dominant és a-Cu, mentre que SH-BimH-5NH2 mostra potencial com a inhibidor en aliatges on el Zn és majoritari i en aliatges CuZr. Les mesures electroquímiques, especialment de llarga durada, mostren una bona correlació amb les anàlisis d'immersió. La recerca realitzada ofereix elements de comprensió del mecanisme de corrosió en presència d'inhibidors. L'oxidació pre-existent de la superfície, els defectes en la superfície i el grup funcional de l'inhibidor són els factors dominants en l'efectivitat dels inhibidors. L'efecte de cicatrització afecta també notablement el rendiment d'alguns inhibidors.

An aged high damping alloy 53Cu 45Mn-2Al was studied both microstructurally by transmission electron microscopy (TEM) and microstructurally with two different damping measurement methods. In-situ heating and cooling observations were made with TEM in order to define the recently discovered flickering phenomenon associated with it's tweed microstructure. TEM studies were also made of an aged 53.6Cu-46.4Mn binary alloy. Damping measurements were obtained by a normalized bandwidth method applied to data from a resonant bar. This was used to determine (i) the aging condition for optimum damping, (ii) the subsequent trend of damping at room temperature for each aging condition, and (iii) the effect of an 8 HR storage at 100C on damping capacity. Damping measurements utilizing a free decay technique to determine log decrement were also used and compared to results from the normalized bandwidth method. Theses. (JES)

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Perkins, Jeff. "June 1990." Description based on title screen as viewed on March 22, 2010. DTIC Identifier(s): Alloys, Spinodal Decomposition, Flickering, Damping. Author(s) subject terms: High Damping Alloys, Spinodal Decomposition, Cu-Mn alloys, Flickering. Includes bibliographical references (p. 85-92). Also available in print.

In the course of this PhD thesis metastable Cu50Zr50-xTix (0≤ x ≤ 10) and (Cu0.5Zr0.5)100-xAlx (5 ≤ x ≤ 8) alloys were prepared and characterised in terms of phase formation, thermal behaviour, crystallisation kinetics and most importantly in terms of mechanical properties. The addition of Al clearly enhances the glass-forming ability although it does not affect the phase formation. This means that the Cu-Zr-Al system follows the characteristics of the binary Cu-Zr phase diagram, at least for Al additions up to 8 at.%. Conversely, the presence of at least 6 at.% Ti changes the crystallisation sequence of Cu50Zr50-xTix metallic glasses and a metastable C15 CuZrTi Laves phase (Fd-3m) precipitates prior to the equilibrium phases, Cu10Zr7 and CuZr2. A structurally related phase, i.e. the “big cube” phase (Cu4(Zr,Ti)2O, Fd-3m), crystallises in a first step when a significant amount of oxygen, on the order of several thousands of mass-ppm (parts per million), is added. Both phases, the C15 Laves as well as the big cube phase, contain pronounced icosahedral coordination and their formation might be related to an icosahedral-like short-range order of the as-cast glass. However, when the metallic glasses obey the phase formation as established in the binary Cu-Zr phase diagram, the short-range order seems to more closely resemble the coordination of the high-temperature equilibrium phase, B2 CuZr. During the tensile deformation of (Cu0.5Zr0.5)100-xAlx bulk metallic glasses where B2 CuZr nanocrystals precipitate polymorphically in the bulk and some of them undergo twinning, which is due to the shape memory effect inherent in B2 CuZr. Qualitatively, this unique deformation process can be understood in the framework of the potential energy landscape (PEL) model. The shear stress, applied by mechanically loading the material, softens the shear modulus, thus biasing structural rearrangements towards the more stable, crystalline state. One major prerequisite in this process is believed to be a B2-like short-range order of the glass in the as-cast state, which could account for the polymorphic precipitation of the B2 nanocrystals at a comparatively small amount of shear. Diffraction experiments using high-energy X-rays suggest that there might be a correlation between the B2 phase and the glass structure on a length-scale less than 4 Å. Additional corroboration for this finding comes from the fact that the interatomic distances of a Cu50Zr47.5Ti2.5 metallic glass are reduced by cold-rolling. Instead of experiencing shear-induced dilation, the atoms become more closely packed, indicating that the metallic glass is driven towards the more densely packed state associated with the more stable, crystalline state. It is noteworthy, that two Cu-Zr intermetallic compounds were identified to be plastically deformable. Cubic B2 CuZr undergoes a deformation-induced martensitic phase transformation to monoclinic B19’and B33 structures, resulting in transformation-induced plasticity (TRIP effect). On the other hand, tetragonal CuZr2 can also be deformed in compression up to a strain of 15%, yet, exhibiting a dislocation-borne deformation mechanism. The shear-induced nanocrystallisation and twinning seem to be competitive phenomena regarding shear band generation and propagation, which is why very few shear offsets, due to shear banding, can be observed at the surface of the bulk metallic glasses tested in quasistatic tension. The average distance between the crystalline precipitates is on the order of the typical shear band thickness (10 - 50 nm) meaning that an efficient interaction between nanocrystals and shear bands becomes feasible. Macroscopically, these microscopic processes reflect as an appreciable plastic strain combined with work hardening. When the same CuZr-based BMGs are tested in tension at room temperature and at high strain rate (10-2 s-1) there seems to be a “strain rate sensitivity”, which could be related to a crossover of the experimental time-scale and the time-scale of the intrinsic deformation processes (nanocrystallisation, twinning, shear band generation and propagation). However, further work is required to investigate the reasons for the varying slope in the elastic regime. As B2 CuZr is the phase, that competes with vitrification, it precipitates in a glassy matrix if the cooling rate is not sufficient to freeze the structure of the liquid completely. The pronounced work hardening and the plasticity of the B2 phase, which are a result of the deformation-induced martensitic transformation, leave their footprints in the stress-strain curves of these bulk metallic glass matrix composites. The behaviour of the yield strength as a function of the crystalline volume fraction can be captured by the rule of mixtures at low crystalline volume fractions and by the load bearing model at high crystalline volume fractions. In between both of these regions there is a transition caused by percolation (impingement) of the B2 crystals. Furthermore, the fracture strain can be modelled as a function of the crystalline volume fraction by a three-microstructural-element body and the results imply that the interface between B2 crystals and glassy matrix determines the plastic strain of the composites. The combination of shape memory crystals and a glassy matrix leads to a material with a markedly high yield strength and an enhanced plastic strain. In the CuZr-based metastable alloys investigated, there is an intimate relationship between the microstructure and the mechanical properties. The insights gained here should prove useful regarding the optimisation of the mechanical properties of bulk metallic glasses and bulk metallic glass composites.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

Abstract Cu-based shape memory alloys are a promising alternative to the widely used nitinol. The challenge for their use is related to the application temperature, shape memory properties as well as fabrication, and further processing. Knowledge of the transformation temperatures, microstructure, and deformation behavior is of fundamental importance. Research suggested that Cu-Al-Mn shape memory alloys could fulfill this combination of properties excellent. For this purpose, a Cu-Al-Mn-Ni shape memory alloy was melted, cast, and the produced cast rods were subsequently heat treated. For a first idea of whether the chosen composition is a promising alloy depending on the homogenization time, the transformation temperatures and the resulting microstructure were investigated. The transformation behavior was determined by dynamic differential calorimetry. Microstructure investigations were performed by optical microscopy. In addition, to get a first knowledge concerning the deformation behavior the material was characterized by quasi-static compression tests. To this end, cylindrical specimens were turned from the cast bars. The investigation demonstrates a pseudoelastic behavior of the chosen Cu-Al-Mn-Ni shape memory alloy. The study proves the influence of the homogenization time on the microstructure. Furthermore, excellent deformation behavior and good shape memory properties under compressive loading are shown.

In this study, microstructure and mechanical properties of Cu-based amorphous alloy matrix composites consolidated by spark plasma sintering (SPS) equipment were investigated. Amorphous alloy powders were mixed with 10∼40 vol.% of pure Cu powders, and were consolidated at 460°C for 1/2 minute under 300 or 700 MPa. The consolidated composites contained Cu particles homogeneously distributed in the amorphous matrix, and showed a considerable plastic strain, whereas their compressive strength was lower than that of the monolithic amorphous alloys. The compressive strength and plastic strain of the composites consolidated under 700 MPa showed 10∼20% and two times increases, respectively, over those of the composites consolidated under 300 MPa. The increase in consolidation pressure could play a role in sufficiently bonding between prior amorphous powders, in preventing micropores, and in suppressing the crystallization, thereby leading to the successful consolidation of the high-quality composites. Microfracture mechanisms were investigated by directly observing microfracture processes using an in situ loading stage. Cu particles present in the composites acted as blocking sites of crack propagation, and provided the stable crack growth. These findings suggested that the composites consolidated by the SPS presented new possibilities of application to structural materials or parts requiring excellent mechanical properties and large sizes.

Abstract The present study highlighted the effect of alloying elements in Al alloy on the interfacial microstructure, and the corresponding fracture behaviour of the Al alloy/steel inertia friction welded joint by selectively adopting two types of Al alloys. A strong texture of &lt;111&gt;//radial direction was formed on the Al alloy side in both types of joints, while no obvious changes were identified on the steel side. Different types of intermetallic compounds (IMCs) were formed at the weld interface. In the Al-Mg-Si alloy/steel joint produced at a low heat input, the interfacial microstructure was composed of a nanoscale amorphous layer and partially crystallised layer, while it turned into a fully crystallised Fe2Al5 phase with Si enriched when the heat input was enhanced. In the Al-Cu alloy/steel joint, Cu was enriched at the weld interface, with the possible formation of Fe-Al-Cu based IMCs. Moreover, a two-layered structure of IMC with different compositions of Cu appeared when the joint was prepared at a high heat input. Such distinct interfacial microstructure caused different fracture behaviours of joints. An interfacial reaction layer less than 130 nm thick led to the failure of Al alloy rather than the weld interface which easily happened at a thicker IMC.

Abstract The effect of hydrogen on the deformation and fracture behavior in pure Cu, pure Ni and Cu–Ni alloy was studied via tensile tests of H-charged, smooth and circumferentially-notched specimens at room temperature (RT) and 77 K. Hydrogen-diffusion properties were determined by the desorption method. To obtain a uniform hydrogen concentration in the H-charged specimens, specimens were exposed to 100-MPa hydrogen gas at 543 K for 200 h, based on the determined hydrogen diffusivity. In tensile tests of smooth pure Ni and Cu–Ni alloy specimens at RT, common hydrogen effects were detected, namely, an increase in yield and flow stresses — a hardening effect; and a ductility loss that was accompanied by a change in fracture surface from ductile to brittle feature — an embrittling effect. With regard to the embrittling effect, the pure Ni and Cu–Ni alloy showed different fracture-surface morphologies at RT; the pure Ni showed an intergranular (IG) surface and the Cu–Ni alloy surface was flat. However, a number of IG cracks were detected beneath the fracture surfaces on the smooth Cu-Ni alloy. The tensile tests of the H-charged smooth specimens at 77 K yielded an IG surface for the pure Ni and a ductile fracture surface with dimples in the Cu–Ni alloy. In contrast, tensile tests of the H-charged, notched specimens at RT demonstrated clear IG fractures for the pure Ni and Cu–Ni alloy. These facts indicate that IG cracking was the first step in the embrittling process for the pure Ni and Cu–Ni alloy, and IG cracking was accompanied by a large plastic deformation that formed the flat surface (unclear IG surface) for the smooth Cu–Ni alloy. Considering that the HE of both pure Ni and Cu–Ni alloy was related to IG cracking, possible mechanisms were discussed and tensile tests performed at 77 K suggested two possibilities: (I) interaction between hydrogen-moving dislocation is more important in the HE process of the Cu-Ni alloy compared to the pure Ni; (II) hydrogen transportation towards grain boundaries are required to cause the IG fracture in the Cu-Ni alloy.