Research on Ti-Al-Nb Coating by Laser Alloying on TC4 Titanium Alloy

Abstract:

Ti-Al-Nb alloy coating is successfully fabricated on the surface of TC4 titanium alloy by laser alloying using Ti, Al, Nb milled powders as the raw material. The phase composition, microstructure and micro-hardness of the coating are investigated. The friction wear property of the coating is tested with the YG6 ball as counter-body under dry lubrication. The results show that under the laser power 1.8kW,scanning speed 5mm/s and spot diameter 2mm, the coating is uniformdense and crack-free, and it has a good metallurgical combination with the TC4 substrate. Microstructure of the coating mainly consists of Ti₃Al, AlNb₂ and α-Ti. The micro-hardness of the coating (between 580 ~ 630HV) is significantly higher than that of the TC4 matrix (350~360HV). The friction coefficient of Ti-Al-Nb coating is reduced (0.33 vs. 0.45) and the wear resistance is 2.95 times greater than that of the substrate.

Key words:TC4 titanium; laser alloying; composite coating; microstructure; friction wear properties