Cai Zhaobing, Cui Xiufang, Jin Guo, Liu Zhe, Li Yang, Dong Meiling
Institute of Surface/Interface Science and Technology, Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, Harbin 150001, China; College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China.
College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China.
Micron. 2017 Dec;103:84-89. doi: 10.1016/j.micron.2017.10.001. Epub 2017 Oct 5.
Phase separation is a common phenomenon in traditional alloys. Under the condition of appropriate undercooling, the segregation phenomenon can be also found in blue-chip high-entropy alloys (HEAs). In this work, the phase separation behavior and interfacial investigation of laser surface alloyed HEA coating with high content Ti were studied principally by transmission electron microscopy. The results show that crystal structure and elementary composition on both sides of the interface of coating/substrate are quite different, and the interfaces between different phases are incoherent or semi-coherent boundarys, resolved by high resolution transmission electron microscopy. In the interface of (Co, Ni)Ti phase/β-Ti phase, there is angle of 80° between BCC〈100〉 and FCC〈201〉. An interesting 'island' structure, that β-Ti phases are embraced by (Co, Ni)Ti compounds in the BCC matrix, was observed definitely, which is attributed to the combined action of Ti segregation and inter-attraction of Ti and other elements.
相分离是传统合金中的常见现象。在适当过冷条件下，在优质高熵合金（HEA）中也能发现偏析现象。在本工作中，主要通过透射电子显微镜研究了高含量Ti的激光表面合金化HEA涂层的相分离行为和界面。结果表明，涂层/基体界面两侧的晶体结构和元素组成差异很大，不同相之间的界面是不连续或半连续边界，通过高分辨率透射电子显微镜得以分辨。在(Co, Ni)Ti相/β-Ti相的界面中，体心立方〈100〉与面心立方〈201〉之间存在80°夹角。明确观察到一种有趣的“岛状”结构，即在体心立方基体中，β-Ti相被(Co, Ni)Ti化合物包围，这归因于Ti偏析以及Ti与其他元素的相互吸引的共同作用。
