Zr-Cr-Fe合金马氏体相变过程中三变体团簇的择优形成及其晶体学分析

The preferred formation and crystallographic analysis of three-variant cluster in Zr-Cr-Fe alloy during martensitic transformation

摘要:

采用ECC, TEM和EBSD表征技术,研究了Zr-Cr-Fe合金经β相淬火后的马氏体组织特征。结果表明：马氏体相变过程中,任一高温β相都能够转变为12个α马氏体变体。而这12个α马氏体变体并不是随机分布的,而是择优形成了四个亚区域。每一个亚区域由一种三变体团簇组成,而该三变体团簇表现为典型的三角形自我协调形貌。进一步晶体学分析表明：组成每一个团簇的这三个马氏体变体与母相之间存在一个共同的 极点,同时该三变体相互之间的取向关系为 。由于在β→α马氏体相变过程中存在形状应变,而三变体团簇的形成能够最大程度的协调该应变。

关键词:Zr-Cr-Fe; Burgers取向关系; 自我协调; 三变体团簇;

Abstract:

The martensitic microstructure of Zr-Cr-Fe alloy after β-quenching are investigated by a combination of electron channeling contrast imaging (ECC), transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques. All of theoretical 12 α variants inherited from one single β phase have been obtained in the current study that revealed strict Burgers orientation relationship (BOR) with respect to β parent phase. The entire martensitic microstructure consisting of these 12 α variants in the as-quenched Zr-Cr-Fe alloy can be divided into four sub-regions or morphological groups. Each sub-region, in turn, is dominated by only one type of three-variant cluster (one crystallographic group composed of three α variants) showing the self-accommodation triangular morphologies. These three variants from individual cluster share a common pole of β parent phase and are related to each other by an angle/axis pair . The preferred formation of such three-variant cluster is ascribed to the elastic interaction between variants to achieve the largest degree of self-accommodation.

Key words:Zr-Cr-Fe alloy; Burgers orientation relationship; Self-accommodation; Three-variant cluster;