Stabilization of Ti5Al11 at room temperature in ternary Ti-Al-Me (Me = Au, Pd, Mn, Pt) systems

Ti5Al11 is known as a high-temperature phase in binary Ti-Al alloys. However, its existence at low tem-peratures was previously observed in ternary Ti-Al-based systems alloyed with some transition metals. In this study, we systematically evaluated Ti-Al-Me ternary systems (Me = Au, Pd, Mn, or Pt) to determine the influence of transition elements on low-temperature stabilization of Ti5Al11 phase. The temperature ranges in which Ti5Al11 existed in Ti-Al-Me systems were experimentally found using in situ synchrotron X-ray diffraction (SXRD). It was established that addition of Mn and Pt retains Ti5Al11 at room temperature. The obtained data were compared with predictions of density functional theory (DFT). The total energy, volume, and bond length are especially significantly reduced by addition of Mn and Pt. Ti5Al11 compound containing both of these elements is less prone to saturation with Ti upon preserving the lattice tetragonality and suppressing Ti5Al11 -> TiAl transformation. These factors finally contribute to the retention of this phase at room temperature.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

It has been found that the addition of transition metals Mn and Pt can retain the Ti5Al11 phase at room temperature. Through experiments and density functional theory predictions, it was discovered that the addition of Mn and Pt significantly reduces the total energy, volume, and bond length of the Ti5Al11 compound, thereby suppressing the Ti5Al11 -> TiAl transformation and preserving the lattice tetragonality, ultimately leading to the retention of the Ti5Al11 phase at room temperature.