【摘要】 本工作借助激光熔覆技术，在45钢上开展不同Cr₃C₂添加量的Ni₃Al+Cr₃C₂混合粉末制备Ni₃Al基合金激光熔覆层试验研究，利用扫描电镜、X射线衍射仪、透射电镜及摩擦磨损试验机等设备，统计不同Cr₃C₂添加量下原位自生碳化物的含量及尺寸，分析碳化物对Ni₃Al基合金熔覆层显微组织、显微硬度及摩擦磨损性能的影响。结果表明：Ni₃Al基合金激光熔覆层组织主要为Ni₃Al基相和原位自生的Cr₇C₃碳化物。随着Cr₃C₂含量的增加，熔覆层原位自生碳化物含量由6.8%增加至32.3%，平均尺寸由0.10μm增长至0.78μm，熔覆层显微硬度（HV）由4615.8 MPa提高至5968.2 MPa。当Cr₃C₂含量为35%时，碳化物呈小颗粒弥散分布，摩擦磨损过程中产生均匀磨损，使熔覆层磨损量低至0.19 mg，此时对磨盘的磨损量相对最低，约为1.23 mg；而当Cr₃C₂含量为45%时，碳化物含量虽然达到32.3%，但多以大尺寸颗粒为主，在摩擦磨损过程中大颗粒碳化物发生断裂剥落，加速了对磨盘的磨损。更多还原

【Abstract】 Using Ni₃Al+Cr₃C₂ mixed powder with different Cr₃C₂ contents as raw materials,Ni₃Al-based alloy laser cladding layer was prepared on 45 steel by laser cladding technique.The content and average size of in-situ-formed carbides with different Cr₃C₂ contents were calculated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,and friction and wear testing machine,and the effects of carbides on the microstructure,microhardness and wear resistance of Ni₃Al-based alloy cladding layer were analyzed.The results indicate that the microstructure of the Ni₃Al-based alloy laser cladding layer contains mainly Ni₃Al matrix and in-situ-formed Cr₇C₃ carbides.With the increase in Cr₃C₂ content,the proportion of in-situ-formed carbides in cladding layer is increased from 6.8%to 32.3%,the average size is increased from 0.10μm to 0.78μm,and the microhardness（HV） of the cladding layer is increased from 4615.8 MPa to 5968.2MPa.When the content of Cr₃C₂ is 35%,the carbides are dispersed as small particles,and uniform wear occurs in the process of friction and wear test,so the wear loss of cladding layer is as low as 0.19 mg,and the wear loss of the disk is relatively the lowest,about 1.23 mg.However,when the content of Cr₃C₂ is 45%,the carbide content reaches 32.3%,and the carbides are mainly large size particles.In the process of friction and wear test,the large carbides particles break off,which accelerates the wear of the grinding disk.更多还原