Effects of composition on phase stabilities and elastic properties in TiZrAlV alloys：Experiments and first-principles calculations

Abstract

Phase stability and the elastic properties of α, β, α" and ω phases in four different component TiZrAlV alloys were studied by first-principles calculations and experiments. The results of Differential Scanning Calorimetry (DSC) and X-ray Diffractometer (XRD) showed that α, β, α" and ω phases could be stabilized in four alloys except β phase in TZA8 alloy. Varied compositions and phases in the alloys lead to different Young’s modulus E. First-principles calculations were used to verify the experimental results in the four TiZrAlV alloys. Four atomic configurations of TiZrAlV systems with β, α", α and ω phases were obtained using approximate simplified atomic ratios. These 16 models were calculated to investigate their phase stabilities and elastic properties by means of electronic structure, formation enthalpy ΔHf and elastic properties. The density of states (DOS) of β phase in TZA8 alloy without pseudogap near Fermi level (EF) suggested that β phase was unlikely to exist in the TZA8 alloy, which agreed with the experiment results. From the results of energy calculations, β-phase was found to be more structurally stable compared to α, α" and ω phases in TZA12V6 and TZA12V4 alloys. α"-phase in alloys TZA14V8, TZA12V6 and TZA12V4 and β-phase in TZA8 alloy had the lowest stability. The results of elastic properties showed that Young’s modulus was affected by alloy composition and phase, and β-phase had the characteristics of lower Young’s modulus and better plasticity than other phases in the TiZrAlV alloys. The results of experiments and first-principles calculations manifested that the compositions affected the phase stabilities and the elastic properties of the TiZrAlV alloys.