Dynamic equilibrium of MoSi2 polymorphs during mechanical milling

The phase transformation of α-MoSi2 into β-MoSi2 induced by mechanical milling (MM) was studied. Planetary ball milling was performed on an α-MoSi2 powder under six different milling conditions. The X-ray diffraction results show that the dynamic equilibrium between α-MoSi2 and β-MoSi2 is reached at low milling intensities, while a single phase of β-MoSi2 is formed when milled at high milling intensities. The single-phase β-MoSi2 formation is found to be due to Fe impurity. The mechanism of the phase transformation of MoSi2 is discussed, and the phase fractions under the dynamic equilibrium are explained by the redistribution of the close-packed layers via synchroshear processes.

► Ball milling on a MoSi2 powder with varying the revolution speed and the ball-to-powder weight ratio.
► The dynamic equilibrium between the α- and β-MoSi2 phases is reached with low milling intensities.
► The single phase of β-MoSi2 is produced with high milling intensities due to Fe impurity.
► The transformation probably proceeds via synchroshear processes.