Stability of pseudotwins in D03-type alloys calculated from first principles. (1st May 2016) - Mizuno, Masataka
Abstract: We investigated the stability of pseudotwins in D03 -type Fe3 Ga, Fe3 Al, Fe3 Ge, and Fe3 Si using first-principles calculations. We found that the energy required to introduce pseudotwins is lowest in Fe3 Ga. In Fe3 Ga, the calculated energy difference between the D03 matrix and the pseudotwin agrees well with the experimental value. We explored the energy landscape for transition from the pseudotwin to the D03 matrix and found that there is no energy barrier in the recovery process for the alloys studied. This is owing to the decrease in lattice distortions by structural relaxations caused by the difference in the recovery rate between the pseudotwin layers. The twin boundary plays an important role in inducing structural relaxation: the strain recovery becomes slower with increasing distance from the twin boundary. In contrast to the continuous decrease in the shear strain of the pseudotwin layers in Fe3 Ga and Fe3 Al, the shear strain in Fe3 Si and Fe3 Ge decreases discontinuously and the twin shear disappears at the transition point. The difference in electronic structures between D03 and the pseudotwin layers is discussed. Graphical abstract: