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 ~ ⊥ to CD, which favored {1012}〈1011〉 extension twins (ET). The ETs nucleate, broaden and engulf the parent matrices with strain, rotating the lattice by ~ 86.4° about 〈2110〉 axes to a geometrically hard orientation with c-axis ~∥ to 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 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 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 ~∥ to CD, the geometrically hard orientation.

Bioimplant grade hot-rolled magnesium with equiaxed microstructure and basal texture was examined for fracture toughness (FT) anisotropy using fatigue pre-cracked single-edge notch bending specimens with the notch, a_n ||, ⊥ and 45° to rolling direction (RD). Due to adequate crack-tip plasticity, the size-independent elastic-plastic fracture toughness (J_IC) were determined. Anisotropic J_IC was observed due to different twin lamellae formation w.r.t. notch owing to the initial basal texture with $\{10\overline{1}0\}$ and $\{11\overline{2}0\}$ poles mostly || and ⊥ to RD. The out-of-plane tensile stresses activated the $\{10\overline{1}2\}⟨10\overline{1}1⟩$ extension twins (ET) as usual with matrix-ET Σ15b coincident site lattice boundary (CSLB) interfaces. While the in-plane tensile stress ⊥ to the crack-tip activated $\{10\overline{1}1\}⟨10\overline{1}2⟩$ contraction twins (CT) that transform into $\{10\overline{1}1\}$- $\{10\overline{1}2\}$ double twins (DT) with matrix-DT Σ23b and Σ15a CSLBs. For a_n || RD, large DT lamellae fraction formed at ~30° and few ETs at ~30° and ~90° to the notch with crack growth mainly via the Σ23b/Σ15a CSLB interfaces during FT. While, significant DT and ET lamellae developed at ~0° and ~60° with cracking via the matrix-DT Σ23b/Σ15a and matrix-ET Σ15b CSLBs for a_n ⊥ RD. The DT and ET lamellae activated at ~15°, and the crack propagated through Σ15b for a_n ~45° to RD. The J_IC and the crack-tip plastic zone decreases, while the elastic component of the J-integral (J_el) and the ET formation increases from a_n ||, ⊥,  to ~45° to RD. The strain incompatibility of matrices was higher with the geometrically hard ETs than DTs. Thus, brittle interlamellar cracking occurred through the Σ15b interfaces. In contrast, almost similar and higher crack-tip plasticity occurred in matrix and DT domains during crack propagation via Σ23b/Σ15a CSLBs. Crack growth through Σ23b/Σ15a led to high J_IC, both Σ15b and Σ23b/Σ15a led to moderate J_IC, and Σ15b least J_IC for a_n ||, ⊥ and 45° to RD, respectively.

In this work, anisotropic fatigue crack growth rate (FCGR) behaviour in a hot-rolled Mg-3wt%Al-0.5wt%Ce alloy was investigated using compact tension (CT) specimens with notch (a_n) parallel to the rolling direction (RD) and transverse direction (TD). The FCGR tests were conducted at a constant load ratio (R = 0.1) and maximum stress intensity factor (K_Max = 15.6 MPa√m) to investigate the crack closure effect. For both constant R and K_Max conditions: (i) the load-displacement curves for every loading cycle were linear for a_n ∥ to RD and TD, indicating no crack closure; (ii) the FCGR was found to be lower for a_n ∥ RD than a_n ∥ TD over the entire stress intensity factor range (ΔK). The hot-rolled sample contained long-aligned Al₁₁Ce₃ intermetallic phase within grain boundaries that are elongated along RD. During the FCGR test, {1012} {1011} extension twins (ET) with lamellae ∼⊥ and c-axis ∼∥ to these elongated intermetallics along RD developed irrespective of the notch orientation. During the loading cycle, these intermetallics along RD generate back-stresses, reducing the in-plane tensile stress ∼∥ and ∼⊥ to crack-tip to ~ 0 for a_n ∥ to RD and TD, respectively. Hence, lenticular ET ~⊥ and ~∥, with c-axis ~∥ and ~⊥ to crack path activates, leading to trans and inter lamellar crack for a_n ∥ to RD and TD, respectively, and anisotropic FCGR. Translamellar crack in a_n ∥ RD reduces the FCGR due to plastic energy dissipation as perceived by comparatively more geometrically necessary boundaries (GNBs). On the other hand, faster FCGR was obtained for a_n ∥ TD due to interlamellar cracking. Thus, the crack growth through the matrix-ET interfaces was favoured due to strain incompatibility. The Fractography for a_n ∥ RD shows smaller elongated grooves along crack propagation, which indicates crack arrest. However, larger elongated grooves for a_n ∥ TD indicated easy crack propagation due to favourable interlamellar crack.