Annealing temperature dependence of crystal structures and magnetic properties of Fe2CrAl and Fe2CrGa Heusler alloys

The crystal structures, spontaneous magnetic moment, Is, and the Curie temperature, TC, of Fe2CrAl and Fe2CrGa Heusler alloys were investigated. Single phases of A2, B2 and L21-type structures were obtainable in Fe2CrAl alloy by controlling the annealing temperature. The values of the Is and TC of the A2-type phase were 2.2 μB/f.u. and 316 K and those of the B2-type phase were 2.0 μB/f.u. and 274 K, larger than those of the L21-type phase of 1.6 μB/f.u. and 210 K, respectively. A single phase of the A2-type phase in Fe2CrGa alloy was obtained and the Is and TC were about 2.8 μB/f.u. and 353 K, respectively. The B2 or L21-type single phases of Fe2CrGa alloy could not be obtained because of the inevitable precipitants.

► We systematically examine the annealing effects on magnetism of Fe2CrAl.
► The magnetism of Fe2CrAl is sensitive to the degree of order.
► Order–disorder phase transition temperature of Fe2CrAl and Fe2CrGa are investigated.
► Fe2CrGa exhibits two phase state in lower temperature region.