Formation of second phase and its influence on transformation and properties of Ni-Mn-based magnetic shape memory alloys

Ni-Mn-based magnetic shape memory alloys have excellent shape memory effects induced by the temperature field and magnetic field, superelasticity, magnetocaloric effect, magnetoresistive effect, elastocaloric effect, exchange bias effect, etc. As a new type of multi-functional material, it is expected to be used in many engineering fields such as actuators, sensors and so on. The research status of Ni-Mn-based magnetic shape memory alloys containing the second phase was described in detail. The formation of the second phase and its influence on martensitic transformation, functional performance and mechanical properties were summarized. Several important and unresolved issues currently were presented, such as the impact of the second phase on magnetic functional properties including magnetic shape memory effect. It was pointed out that in future work, it is essential to study the thermodynamic and kinetic factors of the formation and evolution of the second phase, and properly regulate the second phase so as