不同激光功率下镁合金表面激光熔覆Ni60合金涂层的显微组织和磨损性能

Microstructure and Wear Resistance of Laser Clad Ni60 Alloy on AZ31B Magnesium Alloy in Different Laser Power

为提高镁合金表面的耐磨性,利用5kW横流连续CO2激光器在AZ31B镁合金表面熔覆Ni60合金粉末,制备了无裂纹、气孔等缺陷的熔覆层。分析讨论了不同激光功率下熔覆层的显微组织和磨损性能。结果表明:熔覆层的显微组织为典型的枝晶状态,且随着激光功率的增加,枝晶尺寸增加;不同的激光功率下,熔覆层都由Mg、MgNi2、Mg2Ni3Si、Mg2Ni、Mg2Si和FeNi组成,但当激光功率增加时,Mg相含量逐渐减小,其它相含量逐渐增多。在枝晶细化和各种金属间化合物的共同作用下,熔覆层的显微硬度和耐磨性能都得到提高,且激光功率P=3 000W时,提高程度最大,即显微硬度提高了840%～1 102%,磨损失量是原始AZ31B镁合金的8.57%。

In order to improve the wear resistance of AZ31B magnesium alloy, cladded layer which has no crack and hole was created by a 5 kW continuous wave CO2 laser clad Ni60 alloy powder on AZ31B magnesi- um. The microstructure and the wear resistance of the cladded layer in different laser power is investigated. It is shown that the microstructure of cladded layer is typical dendrite. With the increase of laser power, the dendrite size of the cladded layer increases gradually. With different laser power, the caldded layer is formed by Mg, MgNi2, Mg2 Ni3 Si, Mg2 Ni, Mg2 Si and FeNi, but when laser power increases, Mg decreases relatively to the other phase gradually increases. Because of the recombination action of fined dendritic grain and inter-- metallic compounds, the microhardness and wear resistance of cladded layer are both improved, and with the power of 3kW, the increase is the greatest. That microhardness increases 840% to 1 102%, the wear mass is 8.57%of as-received magnesium alloy.