Phase transition of pseudobinary Cr-Al-N films deposited by magnetron sputtering method

Phase transition of pseudobinary Cr1-xAlxN was investigated by synthesizing Cr-Al-N films using a reactive magnetron sputtering method. It was found that the crystal structure of the pseudobinary Cr-Al-N films changes from B1 (NaCl) type to B4 (wurtzite) type at the AlN content between 67 mol% and 75 mol%. The critical composition for the transition from B1 to B4 shows good agreement with the composition (77 mol% AlN) predicted by the two band parameters. The crytallinities of the Cr-Al-N films with B1 type structure became higher with increasing content of CrN and the lowest crystallinity was observed in the B4 type Cr-Al-N films with the AlN content around 75 mol%, which is very close to the critical composition for B1/B4 phase transition. (C) 1997 Elsevier Science S.A.