First-principles investigation of structural, mechanical and electronic properties for Cu–Ti intermetallics

Tailoring the microstructure and mechanical properties of Cu–Fe alloy by varying the rolling path and rolling temperature

This article focuses on investigating the effect of printing direction on the mechanical properties of Cu–10Sn alloys prepared by laser powder bed fusion (LPBF) technology. Specimens with different forming angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) were fabricated using LPBF technology, and their mechanical properties were systematically tested. During the testing process, we used an Instron 5985 electronic universal material testing machine to accurately evaluate the mechanical properties of the material at a constant strain rate of 10−3/s. The experimental results showed that the mechanical properties of the specimens were the best when the test direction was perpendicular to the growth direction (i.e., the 0° direction). As the angle between the test direction and the growth direction increased, the mechanical properties of the material exhibited a trend of first decreasing, then increasing, and then decreasing again, which was consistent with the direction of the microtexture of the specimens. The root cause of this trend lies in the significant change in the stress direction borne by the columnar crystals under different load directions. Specifically, as the load direction gradually transitions from being parallel to the columnar crystals to perpendicular to them, the stress direction of the columnar crystals also shifts from the radial direction to the axial direction. Due to the differences in the number and strength of grain boundaries in different stress directions, this directly leads to changes in mechanical properties. In particular, when the specimen is loaded in the radial direction of the columnar crystals, the grain boundary density is higher, and these grain boundaries provide greater resistance during dislocation migration, thus significantly hindering tensile deformation and enabling the material to exhibit superior tensile properties. Among all the tested angles, the laser powder bed fusion specimen with a forming angle of 0° exhibited the best mechanical properties, with a tensile strength of 723 MPa, a yield strength of 386 MPa, and an elongation of 33%. In contrast, the specimen with a forming angle of 90° performed the worst in terms of tensile properties. These findings provide important insights for us to deeply understand the mechanical properties of Cu–10Sn alloys prepared by LPBF.

The increasing demand for materials possessing enhanced mechanical strength, high thermal conductivity, and excellent electrical properties has grown significantly. Cu-matrix composites, especially Cu– Ni, present a promising candidate to fulfill these demands. In this study, Cu–Ni composites were successfully synthesized using powder metallurgy with various additions (0–1.5 wt%) of Yttria (Y2O3)-reinforcement aiming to enhance their mechanical, thermal, and electrical properties. The microstructural investigations demonstrated a uniform distribution of Y2O3 particles and a slight increase in porosity of the Cu–Ni matrix. The Cu–Ni composites with 1.5 wt% Y2O3 showed the presence of Cu2NiZn intermetallic compounds, potentially harming their physical and mechanical properties. Y2O3-reinforcement significantly increased the hardness and led to a moderate rise in the yield and ultimate compressive strengths. The results indicated that the Cu–Ni matrix without Y2O3-reinforcement had the highest coefficient of thermal expansion, which decreased with the addition of Y2O3, potentially leading to improved thermal properties of Cu–Ni composites. This study puts an emphasis on the importance of Y2O3 particles dispersion and on the extent of porosity in enhancing the thermal and mechanical properties of Cu–Ni composites.

The object in this work was to investigate the influence of aging temperature and time and chemical composition on the mechanical and electrical properties of Cu–Fe alloys. Polycrystalline specimens of Cu–0·5–3Fe alloys after solution treatment at 950°C for 1h were aged at temperatures of 400°, 500°, 600°, and 700°C for times of 0·5, 1, 3, and 10h. The methods used for the investigations were: optical and electron microscopy, Mossbauer spectroscopy, electrical resistance measurements, and mechanical tests. The aging of supersaturated solid solutions of iron in copper has a great influence on the structure and properties of Cu–Fe alloys. However, a change in alloy composition does not cause a change in electrical resistance, but influences only the mechanical properties and precipitation kinetics. In the initial stage of aging there are iron clusters present, which grow with aging time into dispersive, coherent γ-Fe particles. The size of the γ-particles increases with temperature and time of aging...

Abstract

Effect of Ti additions on microstructure and mechanical properties of Cu–Cr–Zr alloy

The effects of solute random distribution (RSS) before relaxation and solute short-range ordering (SRO) after relaxation on the mechanical behavior of nanocrystalline Cu–Ag alloys were analyzed by molecular dynamics simulation. It has been found that the mechanical properties of Cu–Ag alloy mechanics with SRO were better than those of Cu–Ag alloy mechanics with RSS. Specifically, during the whole tensile process, compared with sample #1 with SRO structure, sample #2 with RSS structure has stronger strain–stress response ability, more obvious phase transformation process, and narrower shear strain zone on the grain boundary. Furthermore, when the number of Voronoi seeds is examined concerning the mechanical properties of the nanocrystalline Cu–Ag alloy, it becomes apparent that the average flow stress drops as the quantity of Voronoi seeds increases.

Lowering stacking fault energy (SFE) of face-centered cubic (fcc, e.g., Cu) metals by adding alloying elements (e.g., Al) is an effective way to create nanotwins (NTs). In this work, nanostructured Cu thin films with different Al additions (0, 1, 5, and 10 at.%) were prepared by magnetron sputtering deposition on silicon and polymer substrate, respectively, to investigate the effect of lowering SFE on microstructural features and mechanical properties. The Al addition can effectively reduce the SFE of Cu thin films, which in turn promotes the formation of NTs and facilitate the growth of (111) texture but suppresses (100) texture of Cu–Al thin films. Increasing the Al addition to ~10 %, the crossed NTs network emerges in the nanostructured Cu–Al thin films. The combined effect of texture and NTs on hardness and ductility was demonstrated, and an optimal hardness/ductility (6.2 GPa/6.3 %) combination was achieved in the Cu–5.0 at.% Al film. Our findings provide deep insight into tailoring the mechanical properties of Cu nanostructures by Al alloying.

Expansion of chromatic color range and improvement of mechanical properties on Cu–Ge supersaturated solid solution alloys

Effect of γ2 phase evolution on mechanical properties of continuous columnar-grained Cu–Al–Ni alloy

Investigation on the microstructure and mechanical properties of the spray-formed Cu–Cr alloys

The structural properties, phase stabilities, anisotropic elastic properties and electronic structures of Cu–Ti intermetallics have been systematically investigated using first principles based on the density functional theory. The calculated equilibrium structural parameters agree well with available experimental data. The ground-state convex hull of formation enthalpies as a function of Cu content is slightly symmetrical at CuTi with a minimal formation enthalpy (–13.861 kJ/mol of atoms), which indicates that CuTi is the most stable phase. The mechanical properties, including elastic constants, polycrystalline moduli and anisotropic indexes, were evaluated. G/B is more pertinent to hardness than to the shear modulus G due to the high power indexes of 1.137 for G/B. The mechanical anisotropy was also characterized by describing the three-dimensional (3D) surface constructions. The order of elastic anisotropy is Cu4Ti3 > Cu3Ti2 > α-Cu4Ti > Cu2Ti > CuTi > β-Cu4Ti > CuTi2. Finally, the electronic structures were discussed and Cu2Ti is a semiconductor.

Phase stability, mechanical and electronic properties of Hf-Te alloys from first-principles calculations

The Cu–Cr–Ti alloys with different Ti contents were prepared by vacuum induction melting, solid solution, cold deformation, and ageing treatment. The microstructures, mechanical, and electrical properties of Cu–Cr–Ti alloys were investigated under different Ti contents. The results indicate that the increase of Ti content can improve the mechanical properties of Cu–Cr–Ti alloys, whereas its conductivity decreases significantly. After cold rolling by 80% and ageing at 500°C for 60 min, the Cu-0.3Cr-0.05Ti alloy with the hardness, electrical conductivity, and tensile strength are 162.6 HV, 82.2% IACS, and 510 MPa, respectively. The strengthening mechanism of the studied alloys is mainly attributed to the Orowan precipitation and dislocation strengthening. The addition of Ti in the ageing process can retard the growth and coarsen Cr precipitates.

ABSTRACTCu–ZrO2 nanocomposites were produced by the thermochemical process followed by powder metallurgy technique. Microstructure development during fabrication process was investigated by X-ray diffraction, field emission scanning electron microscope and transmission electron microscope. The results show an improved distribution of zirconium dioxide (ZrO2) nanoparticles (45 nm) in the copper matrix, which resulted in the improvement of mechanical properties of Cu–ZrO2 composites. The nanocomposite with 9 wt-% ZrO2 possesses the highest hardness (136.5 HV) and the superior compressive strength (413.5 MPa), resulting in an overall increase by 52 and 25%, respectively. The wear rate of the nanocomposites increased with increasing applied loads or sliding velocity.