The phase stability of MoSi 2-NbSi 2 pseudobinary alloys was examined by Monte Carlo simulation and the cluster expansion technique based on first-principles calculations. We found that formation energies of all possible atomic arrangements exhibited a positive sign, indicating that no stable intermediate phase exists between MoSi 2 with C11 b and NbSi 2 with C40 structures. The C40 phase has significantly greater solubility as well as higher temperature dependence of solubility than C11 b, which agrees with previous experimental reports. Lattice vibration is found to significantly affect the solubility of both C11 b and C40 phases, where its impact naturally increases at higher temperatures. From the analysis of Warren-Cowley short-range-order parameters, the C11 b single phase can be interpreted as a nearly disordered state, while the C40 phase exhibits explicit deviation from the disordered state: C40 prefers Mo-Mo and Nb-Nb like-atom pairs for first-nearest-neighbor coordination, especially around equiatomic composition.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2012 Apr 16|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics