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

摘要

Phase stability and the elastic properties of alpha, beta, alpha '' and omega 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 alpha, beta, alpha '' and omega phases could be stabilized in four alloys except beta phase in TZA(8) 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 beta, alpha '', alpha and omega 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 Delta H-f and elastic properties. The density of states (DOS) of beta phase in TZA(8) alloy without pseudogap near Fermi level (E-F) suggested that beta phase was unlikely to exist in the TZA(8) alloy, which agreed with the experiment results. From the results of energy calculations, beta-phase was found to be more structurally stable compared to alpha, alpha '' and omega phases in TZA(12)V(6) and TZA(12)V(4) alloys. alpha ''-phase in alloys TZA(14)V(8), TZA(12)V(6) and TZA(12)V(4) and beta-phase in TZA(8) alloy had the lowest stability. The results of elastic properties showed that Young's modulus was affected by alloy composition and phase, and beta-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. (C) 2020 Elsevier B.V. All rights reserved.