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

Abstract

• Hot-rolled Mg-3Al-0.5Ce alloy showed anisotropic compressive behavior majorly due to basal texture. • Presence of Al 11 Ce 3 precipitates reduced the basal texture intensity, reducing the stage-II strain hardening. • Sigmoidal flow behavior ∥ to rolling (RD) & transverse direction (TD) due to extension twinning induced geometric hardening. • Parabolic flow behavior ∥ to normal direction (ND) due to slip-based deformation and no twinning. • Long-aligned Al 11 Ce 3 precipitates present within the elongated grain boundaries along RD delay the ET nucleation events. 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 Al 11 Ce 3 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 ∼ ⊥ to CD, which favored { 10 1 ¯ 2 } 〈 10 1 ¯ 1 〉 extension twins (ET). The ETs nucleate, broaden and engulf the parent matrices with strain, rotating the lattice by ∼ 86 . 4 ∘ about 〈 2 1 ¯ 1 ¯ 0 〉 axes to a geometrically hard orientation with c-axis ∼ ∥ to CD , leading to sigmoidal flow and increasing stage-II strain hardening rate (SHR). However, Al 11 Ce 3 weakened the basal texture intensity, reducing the stage-II strain hardening compared to the single-phase Mg alloy investigated earlier. The presence of Al 11 Ce 3 intermetallics delayed the ET nucleation event, which initiates at ε ∼ 0.018 . The ET fraction evolves to ∼ 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 Al 11 Ce 3 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 ∼ ∥ to CD , the geometrically hard orientation.

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