The compositional homogenization control of Cu-Ti alloys prepared by accumulative roll bonding-deformation diffusion process

Abstract

A new process of accumulative roll bonding-deformation diffusion (ARB-DD) with subsequent deformation diffusion heat treatment was proposed to solve the problem of poor composition homogeneity of alloys prepared by conventional accumulative roll bonding-diffusion heat treatment (ARB-DHT). The effects of ARB-DHT and ARB-DD on compositional homogeneity of Cu-Ti alloys were studied in comparison. And the mechanism of compositional homogeneity evolution of ARB-DDed Cu-Ti alloy was revealed. The results show that elements in Cu-Ti alloys prepared by the conventional ARB-DHT process are enriched and show a more obvious periodic distribution characteristic, and the compositional homogenization is poor. However, in ARB-DD process, the deformation process drives the Taylor lattice to reopen and form high-density nano-twin with a lamella width of 50–90 nm. Further, the high density of dislocations and stacking faults provides high diffusion rate channels for element diffusion, which effectively facilitates the diffusion and redistribution of elements in the subsequent diffusion heat treatment process and accelerates the compositional homogenization. On the contrary, in comparison with the conventional ARB-DHT process which promotes element diffusion through thermal effects, the ARB-DD process uses the synergistic effects of thermal and deformation effects to promote element diffusion, effectively enhancing the degree of compositional homogenization.