A Molecular Dynamics Simulation to Shed Light on the Mechanical Alloying of an Al-Zr Alloy Induced by Severe Plastic Deformation

Abstract

In a recent experimental work, as a result of severe plastic deformation, a non-equilibrium solid solution was obtained despite the very limited solubility of zirconium (Zr) in aluminum (Al). This opens up a new path in the development of heat-treatable alloys with improved electrical and mechanical properties, where mechanically dissolved elements can form intermetallic particles that contribute to precipitation strengthening. In the present study, molecular dynamics simulations were performed to better understand the process of mechanical dissolution of Zr within an Al model, with Zr atoms segregated along its grain boundaries. Stress–strain curves, radial distribution functions, and mechanisms of plastic deformation and dissolution of Zr in Al were analyzed. It is revealed that orientation of the grain boundary with segregation normal to the shear direction promotes more efficient mixing of alloy components compared to its parallel arrangement. This happens because in the second case, grain boundary sliding is the main deformation mechanism, and Zr tends to remain within the interfaces. In contrast, the involvement of dislocations in the case of normal orientation of grain boundaries with Zr segregation significantly contributes to deformation and facilitates better dissolution of Zr in the Al matrix. The findings obtained can provide new insights considering the role of texture during mechanical alloying of strongly dissimilar metals.