Accumulative roll bonding of Cu–Zr nanolaminate: Atomistic-scale investigation of structural evolution and grain orientation scatter dependence on rolling parameters

Abstract

Understanding the role of processing parameters on the atomic-level deformation mechanism and structural evolution during an accumulative roll bonding process is a necessity in scaling-up the production of metallic nanolaminates. In this study, we have developed a novel atomistic model of “nano-rolling” to investigate the effect of roller speed and temperature on the deformation behavior of Cu–Zr nanolaminate. The model takes both the compressive and the shear forces into consideration during the rolling process, making it efficient in reproducing the actual deformation mechanisms. Results from the mobility analysis have shown that the final velocity of the rolled specimen obtained from the simulation is close to the theoretical value. The phenomenon of texture evolution is also analyzed through orientation scatter analysis, where it is revealed that increasing the roller speed facilitates the formation of low angle grain boundaries and twins at lower temperatures. However, texture weakening of the rolled specimen has been observed at elevated temperatures due to the increase in fine grained equiaxed structures. Concurrently, the roller speed and temperature dependent deformation mechanism of the Zr-layer is also captured through atomic displacement analysis, which shows the formation of a smooth and wavy Zr-layer. Through Voronoi analysis, it is revealed that the wavy profile of the Zr-layer has a direct influence on the formation of metallic glass at the Cu–Zr interface as a higher number of icosahedral clusters are observed in specimens with a wavy Zr-layer.