Multiphase films bearing Ti₂AlN by pulse plasma hollow cathode nitriding

This study aims to resolve the wear resistance and extend the use of titanium aluminides. A novel method of obtaining multiphase films bearing Ti₂AlN on the Ti-Al alloys is put forward. The Ti _1-xAl_x (x=0.25, 0.33 and 0.47) alloys were nitrided in a pulse plasma hollow cathode environment at 800-900°C for various durations in a mixture of 50%N₂ and 50%H₂ under pressures of 1.50-3.00 torr. The results show that the nitriding gas pressure has a strong influence on the phase structure of the surface films. The forming phases in the films are mainly composed of Ti₂AlN and TiN compounds. The presence of Ti₂AlN in the wear tracks apparently reduces the friction coefficient of the samples. The hardened phase TiN in the film improves the wear resistance of the Ti-33Al alloy.