摘要
利用ATEM研究了铁基多元合金FeCrWNiC激光熔覆层的微观组织、亚稳相结构特征以及高温时效时的亚稳相转变机制。结果表明组织为亚共晶组织,即γ+(γ+M7C3),γ奥氏体为具有较高合金度的过饱和亚稳相,M7C3(M为Cr,Fe,W)为六方结构的Cr基亚稳合金碳化物。熔覆组织在高温时效时存在两类碳化物形成机制,即亚稳γ中析出M23C6、M2C与MC碳化物以及M7C3→M23C6与M7C3→M6C的碳化物原位转变机制。
In situ synthesis of Fe\|Cr\|W\|Ni\|C alloys on a low alloy steel substrate by laser cladding was investigated by analytical electron microscopy with EDAX and PEELS. It was observed that the clad coatings consisted of hypo\|eutectic microstructure, i.e., +(+M\-7C\-3). The \|austenite is meta\|phase with extended solid solution of alloying elements and a great deal of fine structures. The M\-7C\-3 was Cr\|based alloy carbide, with various growth morphologies under laser rapid solidification. After thermally treating, the precipitation of M23C\-6,M\-2C and MC from austenite and in situ transformation of meta\|carbides, such as M\-7C\-3M\-6C and M\-7C\-3M23C\-6 were observed. The microstructure had effect of secondary hardening.
基金
中国科学院重大项目
国家自然科学基金
中国博士后基金