Effect of annealing treatment on microstructure and mechanical properties of Al/Ni multilayer composites during accumulative roll bonding (ARB) process

Al/Ni multilayer composites are produced by accumulative roll bonding process and then annealed with different temperatures and time. Macroscopic images, microstructure and mechanical properties of Al/Ni multilayer composites are investigated. As for the macroscopic images, although there was an edge crack along the rolling direction at the third pass, the defect of composites was not serious and the forming quality of composites was relatively good. The yield strength and elongation of Al/Ni multilayer composites are improved after the annealing treatment; however, with the increase in annealing temperature and time, the yield strength and elongation of Al/Ni multilayer composites are decreased. During the process of annealing treatment, aluminum atoms diffuse in the way of vacancy diffusion, which results in the formation of Al₃Ni intermetallic phase at Al/Ni interface and Kirkendall void in the aluminum side. The content of Al₃Ni intermetallic phase and Kirkendall void would increase with the increase in annealing temperature and time.