Transition metal aluminium nitride (TM-Al-N) thin films are valued for their excellent mechanical (e.g. hardness) as well as protective (e.g. oxidation resistance) properties. This paper addresses the structure and phase stability of group IVB TM-Al-N systems Ti(1-x)Al(x)N, Zr(1-x)Al(x)N, and Hf(1-x)Al(x)N. The predicted stability regions of the rock salt cubic structures are x ≤ 0.7, x ≤ 0.45, and x ≤ 0.45, respectively, while the wurtzite-type single phase field is obtained for x ≥ 0.7, x ≥ 0.68, and x ≥ 0.62 respectively. The predicted phase stability regions and the broad dual-phase transition regions in the case of Zr(1-x)Al(x)N and Hf(1-x)Al(x)N are validated by experiments. Furthermore, the phase transition from cubic to wurtzite with increasing Al content in the alloys is correlated with changes of electronic structure and bonding in the systems.
Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700 Leoben, Austria.
David
D
Holec
Richard
R
Rachbauer
Li
L
Chen
Lan
L
Wang
Doris
D
Luef
Paul H
PH
Mayrhofer