Effect of heat treatment on the hardness of Ti-Mo-N films deposited by RF reactive magnetron sputtering

Abstract

The effects of heat treatment on the microstructure and hardness of Ti-Mo-N films were investigated for various N contents. Ti-Mo-N films were deposited onto a AISI304 stainless steel substrate by reactive RF magnetron sputtering in a mixture of argon (7.5 ccm) and nitrogen (02.0 ccm) gases using a Ti 50Mo50 target. X-ray analysis of the as-deposited films indicated that the main phases of the Ti-Mo-N film produced at nitrogen gas flow rates of (fn2) ≤ 0.2 ccm and >0.3 ccm were bcc-(Ti,Mo) and δ-(Ti,Mo)N phase, respectively. As-deposited films were heat treated in an argon atmosphere at 300-1100°C for 30 min. Hardness was measured using a nanoindentation system. There was almost no change in the hardness of the Ti-Mo-N films deposited at fN2 =2.0 ccm after heat treatment. In contrast, the hardness of the films deposited at fN2 =0.2 and 0.3 ccm was significantly increased by heat treatment at temperatures higher than 900°C In particular, the film deposited at fN2 = 0.3 ccm showed a maximum hardness of approximately 35 GPa by heat treatment at 1000°C for 30 min. X-ray measurements and transmission electron microscopy (TEM) observations indicated that the increment of hardness in the Ti-Mo-N film deposited at fN2 = 0.3 ccm was due to the formation of a bcc-(Ti,Mo) phase in a δ-(Ti,Mo)N phase. © 2010 The Japan Institute of Metals.