Mg-Y-Nd-Zn合金中鲜见变形孪晶带的形成及结构特征

发布时间：2018-02-13 23:13

本文关键词： 镁合金变形孪晶带二次孪生室温变形　出处：《稀有金属》2017年08期 　论文类型：期刊论文

【摘要】：尽管对镁合金中变形孪晶的形成及结构已有大量研究报道,但目前为止对非常规的高指数型孪晶的形成及结构本质特征的了解却仍十分有限。本研究利用透射电子显微镜(TEM)对室温压缩变形的Mg-Y1.1-Nd0.4-Zn0.8(%,原子分数)合金进行了详细的结构表征,结果发现在10%的变形量下该合金中可以形成罕见的{1015}型高指数孪晶带。该类型孪晶带界面取向与理论上的{1015}孪晶界面并不一致,而是近似平行于基体{1011}晶面。在{1015}孪晶板条内可以观察到{1012}二次孪生开动的特征,同时也证实了孪晶板条内存在小角度的晶格取向调整。利用二次孪生加小角度晶格扭转机制可以很好的解释这种孪晶带的形成过程。基于该种机制及晶体学孪生几何分析预测镁合金中其他可能出现的高指数型孪晶带有{1016},{2021},{3031}以及{3032}。通过这种机制形成的高指数孪晶带是表观上与一次孪晶带形貌相似的特殊变形带,其与基体的界面取向应与一次孪晶界面一致。
[Abstract]:Although the formation and structure of deformation twins in magnesium alloys have been widely reported, However, the formation and structural nature of unconventional high exponential twins are still very limited. In this study, the structure of Mg-Y1.1-Nd0.4-Zn0.8wt alloy deformed at room temperature was characterized by transmission electron microscopy (TEM), and the structure of Mg-Y1.1-Nd0.4-Zn0.8wt alloy was characterized in detail by means of transmission electron microscope (TEM). The results show that a rare {1015} type high exponent twin band can be formed in the alloy at a deformation rate of 10%. The interface orientation of this type of twin band is not consistent with the theoretical {1015} twin interface. It is approximately parallel to the {1011} crystal plane of the matrix. The characteristics of {1012} secondary twinning can be observed in the {1015} twin lath. It is also proved that there is a small angle lattice orientation adjustment in the twin lath. The formation process of the twin band can be well explained by using the twinning plus small angle lattice torsion mechanism. Based on this mechanism and crystallographic twinning, the twinning can be well explained. Geometric analysis predicts that other potential high exponential twins in magnesium alloys have {1016}, {2021}, {3031} and {3032}. The high exponent twin bands formed by this mechanism are the special deformation bands which are similar to the primary twin bands on the surface. The orientation of the interface with the matrix should be consistent with the primary twin interface.
【作者单位】：北京工业大学固体微结构与性能研究所;
【基金】：国家自然科学基金项目(50571002,51171004)资助
【分类号】：TG146.22

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