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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。
In-situ synthesis of particle-reinforced iron-based composite coatings was prepared by laser cladding by adding Ti-rich carbide into Fe-C-Si-B powder system. The microstructure was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the formation of martensite and the transformation of substructure were analyzed emphatically. The results show that the cladding layer has no pores and cracks and uniform microstructure. It is a typical hypoeutectic structure composed of martensite, ledeburite, retained austenite and in-situ TiC particles. The martensite in the coating is {211} and <113> sheet-like twinned martensite. The secondary tempering effect makes a large amount of cementite with nano-scale precipitated in the martensite, A certain degree of orientation.