Phase Stability and Ground State Properties of Ni–Mn–Ti Heusler Alloys

The work is devoted to theoretical studies within the scope of the density functional theory of phase stability, structural, magnetic, and mechanical properties of Ni2Mn1 + yTi1 − y (y = 0, 0.25, 0.5, 0.75) Heusler alloys. It is shown that with increasing the concentration of excess Mn, the crystal lattice volume of both austenite and martensite decreases, while the energy difference between these phases increases. The formation energy of all the alloys demonstrates negative values, which indicates the resistance of compositions against decomposition into pure elements. At the same time, the calculation data of the mixing energy and the analysis of elastic constants also predict the stability of all compounds, except for the cubic structure of the Ni2Mn1.75Ti0.25 alloy.