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.