Damping mechanism associated with coupling between antiferromagnetic transition and martensitic transformation

To study the relationship between the martensitic transformation and the antiferromagnetic transition and to develop new twin-based high damping materials, the internal friction and modulus in γ Mn-based Mn–Fe and Mn–Ni alloys were measured. Three internal friction peaks were observed between −100 and 400 °C, namely at the Néel temperature TN, the martensitic transformation temperature MS and 0 °C. They are related to the antiferromagnetic transition, the martensitic transformation and twins in the fct phase. The first is accompanyied by a rapid decreases of modulus at TN. The third, high damping peak is similar to the one observed in Mn–Cu alloys, and is attributed to the fcc–fct martensitic transformation or to fine twins in the antiferromagnetic domains.