锆合金激光熔覆镍基复合层微观组织及界面特征

以Ni35自熔性合金粉末为熔覆材料，采用激光熔覆技术在锆合金表面原位生成了NiZr₂/陶瓷增强镍基涂层.利用金相显微镜、扫描电镜、X射线衍射仪等对熔覆界面附近的微观组织、物相组成及界面结合特征进行分析.结果表明，熔覆层基体组织为NiZr+Ni₁₀Zr₇，增强相NiZr₂以细针状均匀分布在熔覆层上部和底部，块状及棒状的陶瓷相Zr₅（Si_xNi_1-x）₄/Zr（Si_xNi_1-x）分布在熔覆层中部，熔覆层与基体间实现良好的熔焊冶金结合，界面结合区组织不均匀，分布有等轴状NiZr及晶间的α-Zr，熔覆层的显微硬度分布均匀，平均值约为1 100 Hv.

Microstructure and interfacial characteristics of Ni-based composite coating on zirconium alloy substrate by laser cladding

The NiZr₂/ceramic reinforced Ni-based composite coating was in-situ synthesized by laser cladding using Ni35 self-fluxing powder on zirconium alloy substrate. The microstructure, phase constituents and interfacial characteristics were investigated by optical microscope, scanning electron microscope and X-ray diffraction method. Results indicated that the matrix of coating was mainly composed of NiZr+Ni₁₀Zr₇, fine needles NiZr₂ distributed at the top and the bottom, and blocky Zr₅(Si_xNi_1-x)₄/Zr(Si_xNi_1-x) ceramic phase in the middle of the coating. Good metallurgical bonding between substrate and coating was obtained. Heterogeneous microstructure of interface zone was mainly compromised of equiaxial NiZr phase and α-Zr at the grain boundary. The mean value of microhardness of the coating reached 1 100 HV.