ABSTRACTThe stability of the Ti50Pd50-xRux alloy was investigated using first-principles density functional theory within the plane-wave pseudopotential method. Firstly, the Ti50Pd50 gave equilibrium lattice parameter and lowest heats of formation in better agreement with experimental data to within 3%. The heat of formation decreases with an increase in Ru concentration, consistent with the trend of the density of states which is lowered at the Fermi level as Ru content is increased which suggests stability. It was also found that from the calculated elastic constants the structures showed positive shear modulus above 20 at. % Ru, condition of stability. Furthermore, the addition of Ru was found to strengthen the Ti50Pd50-xRux system at higher concentrations. The thermal coefficients of linear expansion for the Ti50Pd31.25Ru18. 75 are higher at low temperature, and that the TiPd-Ru system tends to expand more at low content of 18.75 at. % Ru than at higher content. Partial substitution of Pd with Ru was found more effective as a strengthening element and may enhance the martensitic transformation temperature of the Ti50Pd50 alloy.

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In this study, we investigate the effect of ternary addition on the structural, mechanical properties and temperature dependence of Ti-based as potential shape memory alloys using molecular dynamics approach. We found that binary Ti-Pt alloys exhibit shape memory properties and display possible martensitic transformation from B2 to B19 phases. Partial addition with Zr, Co, Pd, Ir showed preferential ternary high temperature shape memory alloys formation of 6.25 at. % X composition (Ti-Pt-X). We found that the equilibrium lattice constants are in better agreement with the available experimental values. The heats of formation and elastic properties reveal possible composition and phases at temperature above 900 K with good shape memory properties. Their structures were confirmed using the X-ray diffraction patterns at different temperatures.

Ti2AlV alloys are commonly employed as structural materials in electronics, metallurgy, and other industries because of their outstanding properties. Knowledge about their surface properties is lacking and limited at the atomic level. In this work, structural, electronic, and stabilities of Ti2AlV surfaces were investigated using the density functional theory approach. This study also looked at the surface energies and work functions of various surfaces. According to our findings, it was found that the (110) surface is thermodynamically stable with lower surface energy than the (100) surface. It was discovered that the surface energy increases with regard to the thickness of the surface slab. Furthermore, the work function of the (110) surface was found to be increasing than that of the (100) surface. Moreover, the work function was found to increase with increasing number of layers in both surfaces. The partial and total density of states of Ti2AlV (100) and (110) were also studied. It was also found that the Fermi level lies at the minimum curve in the TDOS graphs for the Ti2AlV (110) surface while lies at the maximum in (100) surface.