Slip/twinning activity and theoretical critical shear strengths (τ_max) during room-temperature tensile deformation of as-extruded pure Mg and Mg-1wt.%Y sheets were investigated quantitatively via electron back-scattered diffraction (EBSD), scanning electron microscope (SEM) and first-principles calculation. Slip trace analysis results indicated the relative frequency of the active slip modes transformed from basal slip (100%) for pure Mg, to basal slip (84.8%), prismatic slip (9.7%) and pyramidal slip (5.5%) for the alloy. The proportion of grains containing twins reduced significantly from 20.5% to 5.92% with Y addition. To explain the mechanism for the enhancement of the non-basal slip activity in Mg–Y alloy, the critical resolved shear stress of basal slip and pyramidal II slip were assessed by calculating τ_max. The calculated results showed that the τ_max ratio of the pyramidal II slip to basal slip decreased from 13.7 to 7.5, which may be responsible for the observed enhanced activity of non-basal slip.

滑移/孪生活性和理论临界剪切强度（τ_最大）在室温下，通过电子背散射衍射（EBSD），扫描电子显微镜（SEM）和第一性原理计算定量研究了纯Mg和Mg-1wt。％Y片材在室温下的拉伸变形。滑移轨迹分析结果表明，活性滑模的相对频率从纯Mg的基础滑移（100％）变为合金的基础滑移（84.8％），棱柱形滑移（9.7％）和金字塔形滑移（5.5％）。添加Y后，含孪晶的晶粒比例从20.5％显着降低至5.92％。为了解释在镁-Y合金的非基底滑动的活性增强的机制，基面滑移及锥体II滑移的临界剪切应力，通过计算评估τ_最大值。计算结果表明τ_最大锥体II滑动到基面滑移的比率从13.7降低至7.5，其可以是负责非基底滑移的所观察到的增强的活性。