Mg-RE (magnesium-rare earth) alloys exhibit pronounced in-plane anisotropy of mechanical response under quasi-static monotonic loading resulting from the RE texture, as extensively reported. In this work, an obvious in-plane anisotropy of cyclic deformation behavior was observed in an extruded Mg-3Y alloy sheet during strain-controlled tension-compression low-cycle fatigue (LCF) at room temperature. The extrusion direction (ED) samples displayed better fatigue resistance with almost symmetrical hysteresis loops and longer fatigue life compared with the transverse direction (TD) samples. The influences of texture on the deformation modes, cracking modes, and mechanical behavior of Mg-Y alloy sheets under cyclic loading were studied quantitatively and statistically. The activation of various slip/twinning-detwinning systems was measured at desired fatigue stages via EBSD observations together with in-grain misorientation axes (IGMA) analysis. The results indicate that the activation of deformation modes in the TD sample was featured by the cyclic transition, i.e., prismatic slip (at the tensile interval) →{10–12}tension twinning (at the compressive reversal) → detwinning + prismatic slip (at the re-tensile reversal). In the case of the ED sample, the cyclic deformation was dominated by the basal slip throughout the fatigue life. For cracking modes, intergranular cracking and persistent slip bands (PSB) cracking were the primary cracking modes in the ED sample while the TD sample showed a high tendency of {10–12} tension twinning cracking (TTW cracking). The underlying mechanisms influencing the activation of various slip/twinning-detwinning systems, as well as cracking modes and cyclic mechanical behavior, were discussed.

正如广泛报道的那样，Mg-RE（镁-稀土）合金在由 RE 织构产生的准静态单调载荷下表现出明显的面内机械响应各向异性。在这项工作中，在室温下应变控制拉压低周疲劳 (LCF) 期间，在挤压 Mg-3Y 合金板中观察到循环变形行为的明显面内各向异性。与横向 (TD) 样品相比，挤压方向 (ED) 样品显示出更好的抗疲劳性，具有几乎对称的磁滞回线和更长的疲劳寿命。定量和统计研究了织构对Mg-Y合金板在循环载荷下的变形模式、开裂模式和力学行为的影响。通过 EBSD 观察和晶粒内定向错误轴 (IGMA) 分析，在所需的疲劳阶段测量了各种滑移/孪生-去孪生系统的激活。结果表明，TD样品中变形模式的激活具有循环过渡的特征，即棱柱滑移（在拉伸区间）→{10-12}张力孪晶（在压缩反转）→解孪晶+棱柱滑移（在重新拉伸反转）。在 ED 样品的情况下，循环变形在整个疲劳寿命期间由基底滑移支配。对于开裂模式，晶间开裂和持续滑带（PSB）开裂是 ED 样品中的主要开裂模式，而 TD 样品显示出 {10-12} 张力孪晶开裂（TTW 开裂）的高趋势。