We present a detailed study of strain behavior associated with martensitic transition in polycrystalline Ni45Co5Mn37In13 Heusler alloy. A spontaneous phase transition strain with the value of about 0.4% in this alloy can be acquired by applying and removing magnetic field, exhibiting a large two-way metamagnetic shape memory effect (MSME) with nonprestrain. This effect is originated from magnetoelastic coupling due to a large difference in Zeeman energy between austenitic and martensitic phases. In addition, it was also found that even after three magnetic field cycles at 320 K, the two-way MSME is still reproducible. Such characteristic could be ascribed to a random orientation of martensite variants in present alloy.

Spontaneous strains during martensitic transformation and magnetic-field-induced transformation have been systemically studied for Ni46Cu4Mn38Sn12 Heusler alloy, respectively. A large spontaneous strain with the value of about 0.12% upon martensitic transformation has been observed in this alloy, which is almost three times larger than that in ternary Ni–Mn–Sn alloy. In addition, such a value of strain can be obtained through a fully reverse martensitic transformation induced by a field of about 45 kOe, exhibiting a considerable metamagnetic shape memory effect without any prestrain. This behavior can be attributed to magnetoelastic coupling between stable martensite and metastable fraction of austenite.