稀土对真空熔结镍基自熔性合金涂层组织结构的影响

采用真空熔结的方法在45^#钢母材上获得了稀土。NiCrBSi自熔性合金涂层，借助X射线衍射、SEM及EDX研究了涂层截面的微观组织、相结构及涂层与母材界面附近的组织特征，讨论了稀土的加入对涂层组织结构的影响。结果表明：真空熔结NiCrBSi合金涂层为M基固溶体和分布在固溶体上块状、球状和针状的CrB，NiaB，Cr3C3和Cr23C6等第二相组成，涂层与母材为良好的冶金结合。添加稀土元素的NiCrB-SiRE合金涂层消除了针状组织，析出了新的硼化物NiB和硅化物Or65Ni25Si，第二相得到了进一步的球化；RE还阻碍了M，Cr，Si等原子向母材的扩散和Fe原子向涂层的扩散，减轻了Fe原子对涂层的“稀释”作用，保证了涂层的化学组成。

Effect of Rare Earths on Microstructure of Vacuum Melting Ni-Based Self-Fluxing Alloy Coatings

The Ni based self fluxing alloy coating containing RE was acquired by the technique of vacuum fusion sintering on the 45 steel. In virtue of X ray diffraction, SEM and EDX, the microstructure and phase structure of coating were investigated, and the effect of rare earth on microstructure of coating was also discussed. The results show that the microstructure of coating is composed of Ni based solution and a lot of massive, globuar and needle harden phase CrB, Ni 3B, Cr 7C 3, Cr 23 C 6, Cr 3Ni 5Si 2 in the sloid solution. The metallurgical binding between the matrix and coating was realized. The NiCrBSiRE coating containing rare earth element make needle microstructure vanished and precipitate new phase NiB and Cr 6.5 Ni 2.5 Si, and get harden phase sphericized further, consequently, rare earth elements also hinder the diffusion of Fe atom from matrix to coating and hold back the dilution of Fe, ensuring the chemical composition of the coating.