The mechanism clarification of Ni-Mn-Fe-Ga alloys with excellent and stable functional properties

► Ni56Mn25−yFeyGa19 alloys (y > 4) exhibit the most excellent thermomechanical stability. ► Ni56Mn25−yFeyGa19 alloys possess the best shape memory effect in comparison with other systems. ► Major factors affecting shape memory effect of two-phase NiMnGa-based alloys are discussed. ► Effect of alloying elements on improving ductility of NiMnGa-based alloys ranks as: Fe > Co > Ni > Cu.