Theoretical investigation of the solubility in (MxM '(2-x))AlC (M and M '(')= Ti,V,Cr)

We have performed theoretical studies of the solubility within (MxM2-x')AlC, where M and M'=Ti, V, and Cr by means of ab initio total energy calculations. The theoretical values of equilibrium volume and the optimized c/a ratios are in good agreement with those of experiments (within similar to+/-4% and similar to+/-1.3%, respectively). Furthermore we show that if x is increased from 0 to 2 the bulk modulus can be increased by as much as 36%. Based on the total density of states analysis as well as the energy of formation, we suggest that the investigated systems show solubility except for the (Cr,Ti)(2)AlC system. This conclusion is consistent with the published work where solubility within the system (V,M)(2)AlC, (M=Ti and Cr) as well as a miscibility gap in the system (Cr,Ti)(2)AlC were experimentally observed [Schuster , J. Solid State Chem. 32, 213 (1980)].