Influence of rare earth Gd addition on the structural and magnetic transitions of Ni-Mn-Ga alloys

Influence of rare earth Gd addition on the structural and magnetic transitions of polycrystalline Ni₅₀Mn₂₉Ga₂₁ ferromagnetic-shape memory alloy (FSMA) are investigated. The results show that different martensitic phase transformation appears in different Gd content. Martensite structure changes from 5 M with 0.1 at% Gd to 7 M when the content of Gd is more than 0.1 at%. The martensitic and reverse martensitic transformation temperatures increase remarkably with increasing Gd content, whereas the Curie temperature almost keeps unchanged at low Gd content and subsequently decreases. Three kinds of Ni-Mn-Ga-Gd alloys are observed according to the sequence of the structural and magnetic transition, whose structural transition temperatures are lower, equal to or higher than the magnetic transition temperature.