Exploration of Structural, Thermodynamic, Magnetic and Mechanical Properties of Martensite Fe₃Pt Alloys: A Density Functional Theory Study

The current study explored the martensite structures of Fe3Pt alloys, specifically Cmmm-Fe3Pt, P63/mmc-Fe3Pt, P4/mmm-Fe3Pt, and R\( \overline{3} \)m-Fe3Pt, aiming to provide a comprehensive understanding of the mechanisms that govern their physical and chemical properties. We have focused on their structural, thermodynamical, magnetic, electronic, and mechanical characteristics, utilizing the Density Functional Theory (DFT) technique. Our study revealed that in addition to the previously reported austenitic cubic Pm\( \overline{3} \)m-Fe3Pt and martensite tetragonal I4/mmm-Fe3Pt with L12 structure, there exist additional Fe3Pt phases that exhibit excellent structural, thermodynamic, magnetic and mechanical properties. The calculated enthalpies of formation were found to be negative and less than -0.39 eV in all the structures considered, indicating thermodynamic stability and formation under experimental synthetic conditions. Moreover, the computed magnetic moments are in the range 2.94 to 3.04 μB, which is relatively comparable to 3.24 μB of the widely reported Pm\( \overline{3} \)m-Fe3Pt alloy. The analysis of the electronic structure also revealed strong magnetism due to the presence of asymmetry in the spin up and down states of the density of states (DOS) plots. To determine the mechanical response of Fe3Pt structures under loading conditions, we computed the independent elastic constants, macroscopic properties and stress-strain relationship under hydrostatic stress. All four phases, but the hypothetical P63/mmc-Fe3Pt showed excellent mechanical stability at ambient conditions and exceptional hardness and resistance to compression in the elastic region 0% ≤ strain ≤ 10%. This evidence is provided by satisfying the Born necessary stability conditions, large bulk modulus and a strong linear relationship fit (R2) of greater than 0.94.