Anisotropic compressive deformation behavior of hot-rolled Mg-3Al-0.5Ce alloy

Abstract

This work investigates the anisotropic compressive deformation of hot-rolled Mg-3Al-0.5Ce alloy and correlates it with microstructure and texture. Hot-rolled alloy had elongated and equiaxed grains with long-aligned Al₁₁Ce₃ precipitates within the grain boundaries along rolling direction (RD) and basal texture along normal direction (ND). Analytical and crystal plasticity-based viscoplastic self-consistent predominant twin reorientation (VPSC-PTR) approaches were employed to simulate the flow curve and texture evolution for deeper insight into the deformation behavior. For compression direction (CD)∥to RD and transverse direction (TD), the basal texture was $\sim \perp$$\sim \perp$ to CD, which favored $\left\{10\overline{1}2\right\}〈10\overline{1}1〉$$\left\{10\overline{1}2\right\}〈10\overline{1}1〉$ extension twins (ET). The ETs nucleate, broaden and engulf the parent matrices with strain, rotating the lattice by $\sim 86.4^{\circ }$$\sim 86.4^{\circ }$ about $〈2\overline{1}\overline{1}0〉$$〈2\overline{1}\overline{1}0〉$ axes to a geometrically hard orientation with c-axis $\sim \parallel \text{to}\text{CD}$$\sim \parallel \text{to}\text{CD}$, leading to sigmoidal flow and increasing stage-II strain hardening rate (SHR). However, Al₁₁Ce₃ weakened the basal texture intensity, reducing the stage-II strain hardening compared to the single-phase Mg alloy investigated earlier. The presence of Al₁₁Ce₃ intermetallics delayed the ET nucleation event, which initiates at $\epsilon \sim 0.018$$\epsilon \sim 0.018$. The ET fraction evolves to $\sim 0.85$$\sim 0.85$, lower than in the previous works on single phase Mg alloy. A reduction in the +ve SHR slope could be observed from ε = 0.03 to 0.06, indicating increased slip activities in this portion of stage-II. Beyond ε = 0.1, decreasing stage-III SHR was observed due to basal 〈a〉, and pyr 〈c + a〉-I and II slip activities in the ET orientation. The difference in the compressive behavior along RD and TD could not be observed due to Al₁₁Ce₃ precipitate's morphology with elongation along RD. For CD∥to ND, the compressive flow behavior was parabolic with decreasing SHR due to slip-based deformation. ET didn't form, and the texture change was negligible, with initial and final textures having basal texture $\sim \parallel \text{to}\text{CD}$$\sim \parallel \text{to}\text{CD}$, the geometrically hard orientation.