Acta mater. 54, 151-156, 2006
P.H. Mayrhofer1,2, F.D. Fischer3, H.J. Böhm3, C. Mitterer2 and J.M. Schneider1
1Materials Chemistry, RWTH Aachen, Aachen,
2Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben,
3Institute of Mechanics, Montanuniversität Leoben,
4Institute of Lightweight Design and Structural Biomechanics,
TU Wien, Vienna, Austria
Ti1-xAlxN films have been shown to exhibit superior
mechanical and thermal properties and are thus widely used for industrial
We have recently reported, that metastable NaCl-structure (c)
Ti1-xAlxN decomposes to form c-TiN and c-AlN domains, and
that the chemical requirement for spinodal decomposition is fulfilled over a
broad composition and temperature range.
Ab initio calculations showed that the maximum metastable solubility limit of
AlN in c-TiN is in the range of 0.64-0.74, depending on the configurational
The enthalpy change for decomposition of supersaturated
c-Ti1-xAlxN into c-TiN and c-AlN has a maximum of ~0.146
eV/at (28.18 kJ/mol) at x~0.61.
Here, we use continuum mechanical investigations in addition to ab initio
calculations to consider also the previously not described contribution of
strain and surface energy on the energetic balance for this decomposition
Based on these results a simple kinetic model for the decomposition process of
c-Ti1-xAlxN can be developed.