Enhanced elastocaloric effect and mechanical properties of Fe-doped Ni-Mn-Al ferromagnetic shape memory alloys

The influence of Fe substitution for Ni on mechanical properties and elastocaloric effect (eCE) in Ni50-xFexMn32Al18 (x = 2, 3 and 4) ferromagnetic shape memory alloys (FSMAs) has been investigated. These alloys undergo a first-order martensitic transformation from B-2 (austenite) to Ll(0) (martensite) on the cooling process. As the Fe content increases, the martensitic transformation temperature shifts toward lower temperature region, and the amount of gamma phase increases gradually in Ni50-xFexMn32Al18 (x = 2, 3 and 4) alloys. Moreover, the maximum compressive strength (1147 MPa) is obtained in Ni46Fe4Mn32Al18 alloy. The application and removal stress of 300 MPa can produce a large adiabatic temperature change of about 5.1 K and no significant degradation of eCE after 30 stress cycles in Ni46Fe4Mn32Al18 alloy. These results show that Ni50-xFexMn32Al18 alloys would be the promising candidates for new multifunctional materials.