WC颗粒增强Ni基合金复合涂层的热处理组织变化

制备了Ni60B合金激光熔覆涂层、微米WC颗粒增强Ni60B合金激光熔覆涂层(WCm)和纳米WC颗粒增强Ni60B合金激光熔覆涂层(WCn),模拟干滑动磨损温升和磨损时间对激光熔覆涂层进行了100～900℃不同温度下的热处理,用扫描电镜、透射电镜和X射线衍射技术等分析了原始激光熔覆涂层的组织以及在不同温度处理后涂层的组织变化,研究了仅在热的作用下,有无WC颗粒强化对涂层组织变化的影响,以及微米WC和纳米WC不同颗粒增强对镍基合金涂层组织变化的作用。分析结果表明:激光熔覆Ni60B涂层随温度上升到700℃,Cr、Fe、C元素发生扩散,碳硼化物形态变化并发生晶型转变,在900℃时才有相析出现象。WCm涂层和WCn涂层随着温度的升高,Ni基固溶体中出现W和Cr、Fe、C的脱溶,各种形态的碳化物组织将发生不同形式的转化。纳米WC的加入使得WCn涂层组织过饱和度增大,出现上述变化的温度降低。

Microstructure Change of WC Particles Reinforced Nickel Based Alloy Laser Cladding Coatings during Heat Treatment

In this paper, Ni60B coating, micrometer WC particles and nanostructured WC particles respectively reinforced Ni60B coatings were prepared by laser cladding technology. Heat treatment at 100～900 ℃ for keeping 1 hour were conducted for the three kinds of coatings. The coatings were analyzed with SEM, TEM and x-ray diffract meter and the effect of WC particles on the microstructure change of the coatings was investigated. The results show that for Ni60B coating supersaturated elements Cr、Fe、C in Ni solid solution occur diffusion and the shapes and crystal structure types of carbide-boride occur change at 700 ℃, moreover phase precipitation phenomenon occurs at 900 ℃. For WCm and WCn coatings, with temperature raise, the W and supersaturated elements Cr, Fe, C in Ni solid solution occur diffusion and even dissolution, shapes of carbides occur changes. Element W supersaturated degree in WCn coating is higher than in WCm,so the microstructure change occur at lower temperature.