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采用激光熔覆在Ti6Al4V合金上制备了WC、TiC增强TiNi/Ti_2Ni双相化合物基复合涂层,并对涂层进行了激光重熔处理,研究了其重熔前后的组织和力学性能变化。结果表明:重熔处理后稀释率由54.0%增加到74.1%,涂层表面变得更为平整。重熔前涂层由作为增强相的灰白色板条状WC固溶体和黑色TiC胞状树枝晶,以及作为基体的TiNi和Ti_2Ni组成。另外,还存在少量细小白色熔化不完全的WC颗粒。重熔后涂层基体中富钛相Ti_2Ni增多而且贫钛相TiNi减少,WC固溶体由粗大板条状转变为细小的等轴状、花状和板条状,白色未熔WC颗粒消失。重熔后涂层的显微硬度变化不大(从1021.7 HV0.1降低到923.7 HV0.1,降低了约10%,而断裂韧性增加了约35%(从3.57 MPa·m~(1/2)增加到4.81 MPa·m~(1/2)),涂层的开裂敏感性降低。
The WC and TiC reinforced TiNi / Ti_2Ni composite coatings were prepared on Ti6Al4V alloy by laser cladding. The coatings were laser remelted and their microstructures and mechanical properties were studied before and after remelting. The results showed that after the remelting, the dilution rate increased from 54.0% to 74.1%, and the surface of the coating became more smooth. The pre-remelt coating consisted of an off-white slat-like WC solid solution and a black TiC dendrite as a reinforcing phase, as well as TiNi and Ti_2Ni as matrix. In addition, there is still a small amount of fine white melting incomplete WC particles. After remelting, the Ti - rich Ti_2Ni phase increased and the TiNi phase decreased, and the WC solid solution changed from coarse lath to fine equiaxed, flower - shaped and lath - like, and the white unmelted WC particles disappeared. After remelting, the microhardness of the coating did not change much (from 1021.7 HV0.1 to 923.7 HV0.1, a decrease of about 10% and a fracture toughness of about 35% (from 3.57 MPa · m ~ (1/2 ) To 4.81 MPa · m ~ (1/2)), the cracking sensitivity of the coating decreases.