This study investigates the effects of the ultrasonic surface rolling process (USRP) on the surface microstructure, texture, and wear behavior of commercial AZ31 magnesium alloy sheet. The application of USRP induces a depth-dependent gradient microstructure characterized by a gradual transition from fine-grained surface layers to coarser-grained regions. Severe plastic deformation at the surface significantly enhances surface microhardness, with values increasing from 63.8 HV in the untreated specimen to 132.9 HV after USRP-4 passes. The thickness of the plastic deformation layer exhibits process-dependent behavior, growing from 200 µm (two passes) to 250 µm (four passes). Wear test results indicate that the wear resistance of the material is significantly enhanced after USRP treatment. This improvement is primarily attributed to the combined effects of the following factors: surface grain refinement, the role of dislocation-induced twinning, increased hardness, the formation of nanoscale secondary phases, introduction of residual compressive stresses, weakened surface texture, and reduced surface roughness. Notably, both friction coefficients and wear volumes show a direct dependence on the number of rolling passes. This study systematically elucidates the underlying mechanisms linking USRP-induced microstructural evolution to enhanced wear performance, providing critical insights for optimizing surface engineering strategies in magnesium alloys.

The low-cycle fatigue behavior of solutionized (T4) and aged (T6) WE43 magnesium alloys was studied at room temperature. The total strain amplitudes (Δε_t/2) were 0.4%, 0.5%, 0.6%, 0.7% and 1.0%. Detailed microstructure evolution was characterized by scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The results showed that plastic strain amplitude decreased with the increasing cycle number in T4 alloy, which is due to the dense persistent slip bands (PSBs) and dynamic precipitates hindering <a> dislocation slip. In contrast, the plastic strain amplitude increases gradually in T6 alloy, which is attributed to the enhanced activation of pyramidal slip. The low-cycle fatigue life of T6 alloy with larger fatigue ductility coefficient is longer than that of T4 alloy. The Coffin-Manson model can accurately predict the fatigue life of T4 and T6 alloys compared to Jahed-Varvani (JV) energy model. For T4 alloy, the fatigue damage mechanism was dominated by basal slip. For T6 alloy, the enhanced pyramidal slip plays an important role to accommodate plastic deformation.

3% Y₂O_3p/ZGK200 composites were subjected to unidirectional rolling (UR) and cross rolling (CR) at 400 ℃ and 350 ℃ followed by annealing at 300 ℃ for 1 h. The microstructure, texture and mechanical properties of rolled and annealed composites were systematically studied. The rolled composites exhibited a heterogeneous microstructure, consisting of deformed grains elongated along rolling direction (RD) and Y₂O₃ particles bands distributed along RD. After annealing, static recrystallization (SRX) occurred and most deformed grains transformed into equiaxed grains. A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR, indicating that rolling path had great influences on texture of the composites. After annealing process, R-texture component disappeared or weakened, as results, a non-basal texture with double peaks tilting from normal direction (ND) to transverse direction (TD) and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites, respectively. The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR. Some Y₂O₃ particles broke during rolling. The fracture of the composites was attributed to the existence of Y₂O₃ clusters and interfacial debonding between particles and matrix during tension, as a result, the ductility was not as superior as matrix alloy.

Effects of rare-earth (RE) and precipitates on twin evolution in cast Mg-10Gd-3Y-0.5Zr (wt.%) (GW103) alloys of solid solution (T4) and aged (T6) states are investigated performing quasi-static room temperature compression tests and microstructural characterization. It is found that both {10–12} and {11–21} extension twins (ET1 and ET2) can appear in the T4 and T6 states but with different emergence sequences. As the aging heat treatment leads to consumption of RE solutes which could inhibit atomic shuffling required for nucleation of ET1 but not ET2, ET2 occurs prior to ET1 in the T4 state, and ET1 emerges before ET2 in the T6 state. The extension twins here mainly coordinate the plastic deformation through the non-Schmid effect. Our results shed light on the influence of RE elements on twin evolution in magnesium alloys and have implications in developing high-performance Mg-RE alloys.