Investigation of phase stability and martensitic transformation of all-d-metal Heusler alloys Fe2CrIr and Fe2CrV

The magnetism, elastic properties, phase stability and martensitic phase transition of the all- d-metal Heusler alloys Fe ₂CrIr and Fe ₂CrV are systematically investigated using first-principles calculations. Compound Fe ₂CrIr containing late transition metal atoms tends to have a Cu ₂MnAl ( L2 ₁)-type structure and exhibits antiferromagnetism. Fe ₂CrV is relatively stable in the Hg ₂CuTi ( XA)-type structure and exhibits ferromagnetism. Differences in mechanical stability under pressure arise from differences in phonon hybridisation. The response of Fe ₂CrIr to external pressure stems from a high pressure-induced martensitic transformation. On the contrary, the pressure inhibited the martensitic phase transition of Fe ₂CrV. The lower the value of C′, the more unstable the cubic phase. This work analyses in detail the different mechanical behaviours of Fe ₂CrIr and Fe ₂CrV under pressure and the mechanism of pressure-induced martensitic transformation, which may improve a new insight for pressure regulated martensitic phase transformation.