Microstructure and elevated temperature wear mechanism of laser clad Ti₅Si₃/NiTi₂ intermetallic composite coating

A wear resistant Ti₅Si₃ reinforced intermetallic composite coating was fabricated on the substrate of BT9 titanium alloy by laser cladding using Ni-44Ti-16Si alloy powders as the raw material. The microstructure of the coating was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometry. The high-temperature sliding wear resistance of the laser clad composite coating was tested at 600°C under the conditions of 10 N the test load, the 0.1m·s^-1 relative sliding velocity, and the 508 m sliding distance. The results indicate that the laser clad wear resistant composite coating has a rapidly solidified microstructure consisting of Ti₅Si₃ primary particles which are uniformly distributed in the NiTi₂/β eutectic matrix and it is metallurgically bonded to the BT9 titanium alloy substrate. It has high hardness and excellent wear resistance under high-temperature sliding wear conditions.