电子束重熔对机械合金化法制备TiC/Ti复合涂层组织及摩擦性能的影响

对机械合金化（MA）法制备的TiC/Ti复合涂层进行电子束重熔处理，分析了经过不同电子束扫描速度的重熔工艺后TiC/Ti复合涂层组织和耐磨性能的变化规律。结果表明，当扫描速度为5~15 mm/s时，重熔处理消除了MA法制备的TiC/Ti复合涂层中的孔隙和裂纹，使其硬度与耐磨性能显著提高；但扫描速度过快（20 mm/s）时，TiC/Ti复合涂层内部出现重熔导致的孔洞缺陷。随着扫描速度由5 mm/s增加至15 mm/s，重熔后TiC/Ti复合涂层中的TiC相由粗大树枝状晶体逐渐转变为弥散分布的短棒和颗粒状晶体，弥散强化作用和固溶强化作用逐渐增强，TiC/Ti复合涂层的硬度由重熔前HV 554逐渐提高至HV 783，磨损速率由5.93×10-4 mm3（N·m）-1逐渐下降至1.75×10-4 mm3（N·m）-1，扫描速度为15 mm/s重熔后TiC/Ti复合涂层的性能最佳。 

Effect of electron beam remelting on microstructure and tribological properties of TiC/Ti composite coating prepared by mechanical alloying

An electron beam was applied to remelt TiC/Ti composite coating prepared by mechanical alloying (MA) method. The microstructure and wear resistance of the coatings were analyzed after electron beam remelting with different scanning velocities. The results show that when the scanning velocity is between 5 mm/s and 15 mm/s, the hardness and wear resistance of TiC/Ti composite coatings are significantly improved due to elimination of the pores and cracks through remelting process. Remelting defects appear inside the coating when the scanning velocity is too fast (20 mm/s). With the increase of scanning velocity from 5 mm/s to 15 mm/s, TiC phase in the TiC/Ti composite coating changes from coarse dendritic crystals to short rod-like and granular crystals gradually, enhancing the dispersion strengthening effect and solid solution strengthening effect. The hardness of TiC/Ti composite coatings increase from HV 554 (before remelting) to HV 783, and the wear rate of the coating decreases from 5.93×10^-4 mm³(N·m)^-1 to 1.75×10^-4 mm³(N·m)^-1 with the increase of scanning velocity. The remelted TiC/Ti composite coating reaches the best performance at the scanning velocity of 15 mm/s.