Mechanical and elastocaloric effect of Fe and Co co-doped Ni–Mn–Al ferromagnetic shape memory alloys

Abstract The martensitic transformation (MT), microstructure, mechanical properties and elastocaloric properties of Ni40FexCo10-xMn32Al18 (x = 2, 4, 6 at.%) polycrystalline alloys were comprehensively investigated. The MT temperature of these alloys shifts to lower temperatures as Fe/Co ratio increases. The fracture strength is significantly enhanced from 905 MPa of Ni40Fe2Co8Mn32Al18 to 1275 MPa of Ni40Fe6Co4Mn32Al18. Among these alloys, Ni40Fe4Co6Mn32Al18 exhibits the best elastocaloric properties. A large temperature change of 6.1 K was obtained by applying a uniaxial stress of 400 MPa, and the temperature change about −5.2 K maintains almost constant after 100 stress cycles in the Ni40Fe4Co6Mn32Al18 alloy. The research results demonstrate an effective method to optimize elastocaloric materials used in solid-state refrigeration field.