Multiple eutectic orientation relationships in undercooled Ni-38wt.%Si eutectic alloy  

过冷Ni-38%Si共晶合金中的多重共晶取向关系

作　　者：Fan ZHANG Hai-feng WANG Cun LAI Jian-bao ZHANG Ya-chan ZHANG Qing ZHOU 张帆;王海丰;赖存;张建宝;张雅婵;周青(西北工业大学凝固技术国家重点实验室先进润滑与密封材料研究中心,西安710072;中国航天科工集团公司第三研究院,北京100074)

机构地区：[1]Center of Advanced Lubrication and Seal Materials,State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China [2]The Third Academy of CASIC,Beijing 100074,China

出　　处：《Transactions of Nonferrous Metals Society of China》2020年第7期1826-1838,共13页中国有色金属学报（英文版）

基　　金：Project(2018-JC007)supported by the Science Fund for Distinguished Young Scholars from Shaanxi Province,China;Project(3102017HQZZ008)supported by the Fundamental Research Funds for the Central Universit ies,China。

摘　　要：Eutectic orientation relationships(EORs) in an undercooled Ni-38 wt.%Si alloy were analyzed by electron backscatter diffraction. A total of seven EORs were identified, and three of them were found at the under-cooling degree ?T≈31 K. It is found that their orientations of the primary NiSi phase are same but the misorientation between the neighboring NiSi2 grains can be either 50° or 60°. The multiple EORs were ascribed to a possible change in the growth direction of the primary phase, the change of the primary phase from the NiSi phase to the NiSi2 phase, and the transition from coupled to uncoupled eutectic growth. The current work shows that epitaxial growth of the second eutectic phase on the primary eutectic phase can obey either a single EOR or multiple EORs, which is a unique phenomenon.采用电子背散射衍射技术分析过冷Ni-38%Si(质量分数)合金中的共晶取向关系,发现在过冷Ni-38%Si(质量分数)合金中总共存在7种共晶取向关系。当过冷度?T≈31 K时,存在3种共晶取向关系,其初生NiSi相的取向相同,但相邻NiSi2晶粒之间的取向差约为50°或60°。多重共晶取向关系的产生归因于初生相生长方向的变化、初生相从NiSi相到Ni Si2相的变化以及生长方式从耦合共晶生长到非耦合共晶生长的转变。第二共晶相外延生长于初生共晶相时可以遵循一种共晶取向关系或多种共晶取向关系,这是一种较为独特的现象。

关 键 词：eutectic orientation relationship epitaxial growth UNDERCOOLING Ni-Si alloy 

分 类 号：TG146.15[一般工业技术—材料科学与工程]