退火对激光熔覆MoFeCrTiWAlNb高熔点高熵合金涂层组织与性能的影响

Effect of annealing on microstructure and properties of laser cladding MoFeCrTiWAlNb high-melting-point high-entropy alloy coating

采用激光熔覆技术在W_6Mo_5Cr_4V_2AlA工具钢表面制备MoFeCrTiWAlNb高熔点高熵合金涂层,利用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机研究退火温度对涂层微观组织、相结构、显微硬度及耐磨性能的影响。结果表明,退火前,涂层组织主要由不规则的颗粒状组织和棒状树枝晶组成,包括体心立方结构固溶体(BCC)和MC相,其平均显微硬度为675.92 HV0.2。退火后涂层的组织逐渐长大,BCC主相峰增强,出现少量的MC和Laves相;950℃退火时显微硬度仅下降6.33%,说明该涂层在950℃下具有较好的抗高温软化性能。涂层经950℃退火后仍保持良好的耐磨性,涂层磨损机理以粘着磨损、磨粒磨损为主。

MoFeCrTiWAlNb high-melting-point high-entropy alloy coating was prepared on W6 Mo5 Cr4 V2 Al A tool steel surface by laser cladding. Effects of annealing temperature on microstructure,phase structure,microhardness and wear resistance of the coating were investigated by means of scanning electron microscopy（ SEM）,X-ray diffraction（ XRD）,microhardness test and friction and wear testing machine. The results show that before annealing,the microstructure of the coating is mainly composed of irregular granular structure and rodlike dendritic crystal,exhibiting body-centered cubic（ BCC） and MC phase with average microhardness of 675. 92 HV0. 2. The grain of the coating grows up gradually after annealing,and the peak of the BCC main phase is enhanced,and a small amount of MC and Laves phases appear. The microhardness of the coating is only decreased by 6. 33% after annealing at 950 ℃,which shows that the coating has better resistance to high temperature softening at 950 ℃. The coating still keeps good wear resistance after annealing at 950 ℃,and the wear mechanism of the coating is mainly adhesive wear and abrasive wear.