EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF ORDER-DISORDER IN CU2ALMN

A combination of X-ray and neutron powder diffract:on has been used to measure the two long range order parameters vs. temperature below the disorder-B2 transition in the ternary alloy Cu2AlMn. The results indi cate that at temperatures just below the critical point the Al + Mn su blattice is enriched in Al. First-principles calculations based on onl y the atomic numbers of Cu, Mn and Al support the experimentally-obser ved preference of Al for the Al + Mn sublattice, and reveal the interp lay between the constituent binary systems that gives rise to this beh avior.