Ordering and phase separation aroullu Ti_(50)Al_(25)Mo_(25) composition in ternary Ti-Al-Mo bcc alloys

摘要

The phase equilibria of bec-hased phases in the Ti-Al-Mo alloy system has been studied from first-principles using a combination of ab initio total energy and cluster variation method (CVM) calculations. A set of effective cluster interaction parameters has been derived from the total energies, already computed, of 18 binary and ternary bce superstructures. These interaction parameters were the input for CVM computation of alloy thermodynamics properties. The CVM has been used to determine the bce composition-temperature phase diagram in the Ti-Al-Mo system and site preference for bce-based phases. The investigation focuses its attention on the discussion about the formation of a two-phase field A2 + B2 around the Ti_(50)Al_(25)Mo_(25) composition to suggest some potential directions for future research and development activities on high temperature bcc based superalloys.