Pressure‐ and Temperature‐Coupling‐Induced Structural Transition and Thermal Properties of Al3TM (TM = Ti, Zr, Hf)

Pressure–temperature‐coupling‐induced structural transition and thermal properties of Al 3 TM (TM = Ti, Zr, Hf) have been studied using the first‐principles calculations combined with the quasi‐harmonic approximation. The enthalpy indicates that Al 3 TM transitions to L12 structure at a specific pressure threshold ( for Al 3 Ti, for Al 3 Zr, and for Al 3 Hf). The fundamental thermodynamic parameters, including thermal equilibrium volume , thermal expansion coefficient α , and heat capacity , do not abruptly change due to the structural transition. Whereas many elastic properties, including elastic constants, shear modulus, and Young's modulus, exhibit abrupt variations. Such as, at structural transition critical boundaries, , , and for Al 3 Ti. shows that Al 3 TM is difficult to oppose hydrostatic pressure, and α indicates that Al 3 TM maintains strong stability under high pressure and its volume expansion is expected to be linear at high temperature. Furthermore, shows that the absorbing capacity or heat‐sinking capacity of Al 3 TM is strong at the low pressure and high temperature. The elastic properties exhibit an increasing trend with increasing pressure, whereas they exhibit a more or less decreasing trend with increasing temperature. Both numerical indicators and 3D images of the elastic anisotropy are derived, revealing that Al 3 TM possesses a high degree of anisotropy.