通过时Mg-12Gd-3Y-0.5Zr合金进行单向拉伸试验,检验晶粒尺寸、温度和应变率对合金力学性能的影响.通过退火处理可以获得不同晶粒尺寸((9.63±0.69)～(94.24士2.41)μm)的试样,拉伸温度分别为20℃、-25℃和-50℃.当温度足够低时,塑性变形由滑移主导的变形方式向孪生主导过渡；同样的情况可在晶粒尺寸变大时发生.变形机制的转变导致Hall-Petch关系中斜率的变化.采用Zener-Hollomon参量来描述温度、应变率对孪生的综合影响.实验结果表明,随着Z参量的变大,孪生发生率增大；当Z值足够大时,变形机制发生转变.%The effect of grain size, temperature and strain rate on the mechanical property of extruded Mg-12Gd-3Y-0. 5Zr alloy tested in tension condition was examined. Samples with grain sizes varying between (9. 63 ± 0. 69) to (94. 24±2. 41)fim were prepared by altering the time of annealing. Tension testing of the samples was carried out at temperature among 20℃, - 25℃ and -50℃. Slip dominated the deformation at high temperature but it gave way to twinning dominated flow when the temperature was lowered. A similar transition was observed when the grain size was increased or the strain rate was raised. The transition was accompanied by a change in Hall-Petch slope. Combined effect of temperature and strain rate on twinning was analyzed by using Zener-Hollomon parameter Z. and it was found that the larger Z led to bigger area fraction of twinning lamellae, and the mechanism of deformation varied when 2 was large enough.
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