Milling-induced polymorphic transformation in MoSi2

Abstract

Abstract The mechanism of phase selection during mechanical milling has been investigated first with a large perspective using an exhaustive number of transformations reported in the literature and next with focusing on the specific system of MoSi2. The former shows that the phases exhibiting smaller values of the volume per one mole of atoms and the number of atoms in a reduced unit cell are preferred during mechanical milling. The latter involves both experimental and theoretical investigations. The dynamic equilibrium between the stable α and metastable β phases is reached with negligible Fe contamination, which is explained by a transformation mechanism based on synchroshear. The β phase formation is promoted in the presence of Fe, which is attributed to the formation of Fe-substituted MoSi2 with Si vacancies according to first-principles calculation results.