The influences of process annealing temperature during cold rolling on microstructure and mechanical properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe near β high strength titanium alloy sheets have been investigated. Results showed that the alloy mainly included the deformation induced dislocation structures after cold rolling but no obvious band structure, twin crystal or martensite were observed in this work. The texture components, which were affected by process annealing, are mainly γ-fiber, α-fiber and weak Goss texture. The γ-fiber of alloy when process annealed at 780 °C (α/β phase field) is stronger than at 830 °C (β phase field), where the Goss texture of alloy with process annealing temperature of 830 °C is more obvious. Results of annealing heat treatments showed that the recrystallization of the cold rolled was basically completed in a relatively short time of 2 min at 750 °C for 2 min. The refinement of grain size led to a significant increase of plasticity compared to rolled alloy. Results of tensile testing of aged alloy display the excellent combination of strength and plasticity, and the cold rolled alloy with process annealed at α/β phase field exhibits the better mechanical properties than at β phase field.

This paper addresses the effects of Ce-rich mischmetal on the microstructure evolution of a 5182 aluminum alloy during annealing and rolling processes. The Ce-rich mischmetal was added to an as-cast 5182 aluminum alloy in an induction furnace, and this was followed by homogenized annealing at 450 °C for 24 h and a rolling operation. The microstructure evolution and mechanical properties’ analysis of the 5182 Al alloy were characterized. The results show that the Ce-rich mischmetal could modify the microstructure, refine the α-Al grains, break the network distribution of Mg₂Si phases, and prevent Cr and Si atoms from diffusing into the Al₆(Mn, Fe) phase in the as-cast 5182 Al alloys. Ce-rich mischmetal elements were also found to refine the Al₆(Mn, Fe) phase after cold rolling. Then, the refined Al₆(Mn, Fe) particles inhibited the growth of recrystallization grains to refine them from 10.01 to 7.18 μm after cold rolling. Consequently, the tensile strength of the cold-rolled 5182 Al alloy increased from 414.65 to 454.34 MPa through cell-size strengthening, dislocation density strengthening, and particle strengthening. The tensile strength of the recrystallization annealed 5182 Al alloy was increased from 322.16 to 342.73 MPa through grain refinement strengthening, and this alloy was more stable after the recrystallization annealing temperature.

This study presents a strategy for the preparation of multiscale α phase by high/low-temperature two-step aging in metastable β titanium alloy, Ti-15Mo-3Al-2.7Nb-0.2Si. The purpose of high-temperature aging is to obtain a number of micro-scale secondary α phases (α_S), besides precipitation-free zones (PFZs). After that, in the second stage of low-temperature aging, the nano-scale tertiary α phase (α_T) precipitates in the PFZs. The second-step aging temperature and the time at low temperature will have an important effect on α_T. On the one hand, with the extension of aging time, the morphology of α_T changes from dot-like to needle-like. Secondly, the increase of the second-step aging temperature will promote precipitation of α_T in PFZs. The strength increases gradually with the accelerated precipitation of α_T, and good plasticity is still maintained. The effect of multiscale α on fracture behavior was investigated by in situ tensile testing. Results show that cracks form a transgranular fracture along the slip line after solution treatment. After first-step aging, the crack easily passes through α_S and forms an intergranular fracture. After second-step aging, the formation of multiscale α phase has a stronger effect in hindering the crack growth, which leads to crack propagation mainly by transgranular fracture. Overall, this study demonstrates that the alloy can be heat-treated to achieve an excellent match between strength and ductility, which is expected to meet the application requirements of structural materials of the new generation of aircraft.

This paper systematically investigates the effect of the Ce modifier on the microstructures and mechanical properties of as-cast 5182 Aluminum alloy. The experimental results indicate that the mechanical properties of the alloy are significantly improved after modification, e. g., the tensile strength increases from 248 MPa to 288 MPa, and the corresponding elongation also enhances from 9.7% to 21.9%. One can attribute the main modification mechanism for the property- enhancement to the microstructural optimizations such as grain refinement, solid-solubility, and second phase variation. The Ce not only refines the grain size of as-cast 5182 Aluminum alloy from 109 μm to 25 μm but also reduces the second phases precipitated near the grain boundaries. Reasons for increased tensile strength are both grain refinement and solid solubility improvement. The increase in elongation is due to the grain refinement and the decrease of the second phases particles precipitated along the grain boundary.

The production of alloys with high strength and toughness concurrently is still a difficult challenge. Here, we designed a simple solution-ageing heat treatment system to control the morphology and density of α in Ti-15Mo-3Al-2.7Nb-0.2Si via different heat treatment temperatures. The experimental results show that Ti-15Mo-3Al-2.7Nb-0.2Si exhibits a synergistic combination of tensile strength (1364 MPa), plasticity (7.8% elongation), and fracture toughness (101 MPa·m^1/2) through solutions in the α/β biphasic region and duplex ageing. Notably, the strength of the alloy after the second step of the ageing process is increased by 15% compared with that after the first step of the ageing process. However, there is less than a 5% reduction in the fracture toughness. TEM observations show that the matrix continues to precipitate denser secondary α during duplex ageing, which causes the strength to increase significantly and causes the fracture toughness to weaken. Our work may provide a novel method to optimize the mechanical properties of alloys by controlling the precipitates.