B元素对激光熔覆AlCoCrFeNiTi高熵合金涂层摩擦学性能的影响

Effect of B Element on Tribological Properties of Laser Cladded AlCoCrFeNiTi High Entropy Alloy Coating

为了增强高熵合金涂层对钢铁零部件的防护作用并探究非金属元素硼的强化作用,采用激光熔覆技术制备AlCoCrFeNiTiB_(x)涂层,并借助X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计和多功能摩擦试验机等仪器,探究不同B含量对涂层显微组织结构和摩擦学性能的影响。结果表明:AlCoCrFeNiTiB_(x)(x=0.05、0.10、0.30)高熵合金(HEA)涂层的晶体结构主要由BCC相和FCC相构成。随着B含量的增加,BCC相增加,晶格畸变加剧。涂层表面平均硬度随着B含量的增加而先增加后减小。高熵合金涂层在10、20、30 N 3个载荷下的平均摩擦系数和磨损率均显著低于GCr15。随着载荷增加,HEA涂层的摩擦系数下降。B元素的添加,有利于降低HEA涂层的摩擦系数和磨损率。AlCoCrFeNiTiB_(0.10)高熵合金涂层具有最低的平均摩擦系数和磨损率,在20 N载荷下比GCr15的平均摩擦系数下降约20.4%、磨损率下降约95.9%。HEA涂层的主要磨损形式为塑性变形控制的逐层剥落。B元素的添加,在提高涂层硬度的同时,有利于促进氧化膜的生成,从而降低了HEA涂层的摩擦系数和磨损率。

For enhancing the protective effect of high entropy alloy coatings on steel components and exploring the strengthening effect of nonmetallic element boron,the AlCoCrFeNiTiB_(x)coatings were prepared using laser cladding technology,and the effect of different B contents on the microstructure and tribological properties of coatings was investigated via various instruments such as X-ray diffractometer(XRD),scan-ning electron microscopy(SEM),microhardness tester and multifunctional friction testing machine.Results showed that the crystal structure of the AlCoCrFeNiTiB_(x)(x=0.05,0.10,0.30)high entropy alloy(HEA)coating mainly consisted of BCC and FCC phases.As the B content increased,the BCC phase proportion rose,and the lattice distortion intensified.The average hardness of the coating surface increased initially and then decreased with the increase of B content.Remarkably,the average friction coefficient and wear rate of the HEA coating at three different loads(10,20 and 30 N)were significantly lower than those of the GCr15 alloy.Moreover,as the load increased,the friction coefficient of the HEA coatings demonstrated a decreasing trend.The addition of element B was beneficial for reducing the friction coefficient and wear rate of HEA coatings.The AlCoCrFeNiTiB_(0.1)HEA coating had the lowest average friction coefficient and wear rate,with a decrease of about 20.4%in average friction coefficient and a decrease of about 95.9%in wear rate compared to GCr15 under a load of 20 N.The main wear form of HEA coating was layer by layer peeling controlled by plastic deformation.In summary,the addition of element B not only improved the hardness of the coating,but also promoted the formation of oxide film,thereby reducing the friction coefficient and wear rate of HEA coating.