Nb对激光熔覆MoFeCrTiWAlNb_x高熔点高熵合金组织与性能的影响

Effect of Nb on microstructure and properties of laser cladding MoFeCrTiWAlNb_x high-melting-point high-entropy alloy

为了获得高性能的涂层材料,采用激光熔覆技术,在W_6Mo_5Cr_4V_2AlA工具钢表面制备MoFeCrTiWAlNb_x(x=1,1.5,2,2.5,3)高熔点高熵合金涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)、硬度计和摩擦磨损试验机等测试手段,研究了Nb对激光熔覆MoFeCrTiWAlNb_x高熵合金涂层组织与性能的影响。结果表明,涂层主要由BCC相、MC相和少量拉弗斯相组成,包括先共晶组织和共晶组织。随着Nb含量的增加,先共晶碳化物数量减少、尺寸增加,呈现不规则颗粒状变化。共晶组织的体积分数逐渐增大,共晶组织中BCC相逐渐增多而(MC)_e相逐渐减少,共晶组织形貌也逐渐由不规则块状小颗粒+棒状枝晶变为大块状颗粒+网状枝晶;涂层硬度逐渐下降,耐磨性逐渐上升,涂层磨损机理以粘着磨损、磨粒磨损为主。

In order to obtain high performance coating material,MoFeCrTiWAlNbx(x=1,1.5,2,2.5,3)high melting-point high-entropy alloy coatings were prepared by laser cladding on W6Mo5Cr4V2AlA tool steel.The effect of Nb on the microstructure and properties of high melting point high-entropy alloy coatings was investigated by X-ray diffractometer(XRD),scanning electron microscope(SEM),microhardness tester and wear resistance tester.The results show that the microstructure of the coating consists of BCC phase,MC phase and a small amount of Laves phase,including the first eutectic and eutectic microstructure.With the increase of Nb content,the number of the first eutectic carbides decreases,but the size increases,and the particles phase change irregularly.The volume fraction of the eutectic microstructure increases with the BCC phase increasing and the(MC)e phase decreasing,and the eutectic microstructure gradually changes from small irregular particles+rod dendrites to bulk particles+network dendrites.The hardness of the coatings decreases gradually with the wear resistance increasing.The wear mechanism mainly consists of the adhesive wear and the abrasive wear in the coatings.