激光熔覆制备颗粒增强铁基复合涂层中马氏体亚结构

通过在Fe-C-Si-B粉末体系中添加强碳化物形成元素Ti的方法,激光熔覆制备了原位合成颗粒增强铁基复合涂层.用扫描电子显微镜和透射电子显微镜对其微观组织进行了研究,重点分析了激光熔覆过程中马氏体的形成和亚结构的转变.结果表明,熔覆层无气孔和裂纹、组织均匀,是一种典型的亚共晶组织,由马氏体、莱氏体、残留奥氏体和原位生成的TiC颗粒组成.涂层中的马氏体是{211},<113>系片状孪晶马氏体,二次回火效应使得马氏体中析出了大量的具有纳米尺度的渗碳体,与马氏体具有一定的取向关系.

Substructure of martensite in particle reinforced Fe-based composite coating by laser cladding

In-situ particle reinforced Fe-based composite coating was produced by laser cladding Fe-C-Si-B base powder containing Ti powder.The microstructure of the coating,especially the formation and transformation of martensite during laser processing,was investigated by scanning electron microscopy and transmission electron microscopy.The experimental results show that the coating has no pores or cracks and the microstructure is homogeneous,which consists of martensite,ledeburite,residual austenite and dispersed in-situ Ti carbide particles.The martensite is {211},<113> twinned martensite.Nanometric carbides are precipitated from martensite due to the second tempering effect.They are demonstrated to be cementite and have an orientation relationship with martensite.