Microstructure and wear resistance of laser clad Ti₅Si₃ reinforced wear resistant intermetallic composite coatings

A wear resistant intermetallic matrix composite coating with Ti₅Si₃ as the reinforcing phase was fabricated on titanium alloy BT9 by laser cladding with Ni-59Ti-21Si 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 spectroscopy. The wear resistance of the composite coating in the dry sliding against SAE52100 steel (GCr15) was evaluated at ambient condition, using AISI1045 steel (45 steel) specimen as the reference. Results indicated that the laser clad intermetallic composite coating had a rapidly solidified homogeneous microstructure consisting of Ti₅Si₃ primary particles uniformly distributed in the NiTi₂-Ti₅Si₃-β eutectic matrix and was metallurgically bonded to the titanium substrate. The laser clad composite coating had high hardness and excellent wear-resistance under dry sliding wear test conditions. This was attributed to the formation of the hard Ti₅Si₃ and NiTi₂ intermetallic phases and the refined microstructure of the coating.