激光能量密度对CoCrFeNiMo高熵合金组织与耐磨性能的影响

Influence of laser energy density on the microstructure and wear resistance of CoCrFeNiMo high-entropy alloy

通过激光熔覆制备不同激光能量密度下的CoCrFeNiMo高熵合金涂层,研究了不同激光能量密度对涂层微观组织、显微硬度和摩擦学性能的影响.研究结果表明,所有CoCrFeNiMo高熵合金涂层的相都由FCC和σ相组成,具为典型枝晶组织,枝晶区和枝晶间区组成分别是FCC相和σ相.随着激光能量密度的升高,涂层显微硬度先升高后下降,和耐磨性成正相关.当激光能量密度为66.7 J·mm^(-2)时,涂层显微硬度达到419.8 HV的最高值,耐磨性最好,其原因是较高硬度提高了涂层抗变形能力,有效抵抗了摩擦副对涂层的磨损.由此可见,高熵合金涂层磨损机制由磨粒磨损、黏着磨损和氧化磨损共同作用形成.

In this study,CoCrFeNiMo high-entropy alloy coatings were prepared using laser cladding technique under different laser energy densities.The influence of different laser energy densities on microstructure,microhardness,and tribological properties were investigated.The results showed that all CoCrFeNiMo high-entropy alloy coatings consisted of FCC andσphases,exhibiting a typical dendritic microstructure,where the dendritic regions and inter-dendritic regions were composed of FCC andσphases,respectively.With the increase in laser energy density,microhardness of the coatings initially increased and then decreased,showing a positive correlation with wear resistance.When the laser energy density was 66.7J·mm^(-2),the microhardness of the coating reached its highest value at 419.8HV,indicating the best wear resistance.It is because that the higher hardness of the coating leads to better deformation resistance,and thus effectively resists the wear caused by frictional forces.The wear mechanism of the high-entropy alloy coatings involved a combination of abrasive wear,adhesive wear,and oxidative wear.