Alloy Design and Fabrication of Ingots of Al–Mg–Li–Ca Light-Weight Medium Entropy Alloys

Matsuyama 790-8577, Japan Alloy designs of light-weight high and medium entropy alloys (LW-HEA and LW-MEA, respectively) are discussed in relation to solving the problem of the empirical alloy parameter, ¦ H mix , and the di ffi culties of the fabrication process. The ingots of newly-designed Al ­ Mg ­ Li ­ Ca LW-MEAs were fabricated by the conventional casting process via crucible melting without using a vacuum furnace, and casting under air atmosphere. The ¦ H mix parameter is the average value of the mixing enthalpy of ¦ H i-j between the two components, i-j, in the multicomponent alloys, and the dispersion of ¦ H i-j cannot be evaluated. The parameter ¤ ( ¦ H mix ) was suggested for the evaluation of the dispersion of ¦ H i-j . The Al ­ Mg ­ Li ­ Ca LW-MEAs were designed based on the empirical alloy parameters, including ¤ ( ¦ H mix ). The alloy ingots of equiatomic AlMgLiCa, non-equiatomic Al 2 MgLiCa, and AlMgLiCa 0.3 were successfully obtained by the conventional casting process. The solidi fi cation microstructure of the ingots in the Al 2 MgLiCa LW-MEA was investigated, with particular focus on the position dependences of the chemical composition, constituent phases, solidi fi cation microstructure, and hardness. The present study clari fi ed that LW-HEAs and LW-MEAs containing Al, Mg, Li, and Ca can be obtained by the conventional casting process under air atmosphere, without