Effect of Dy addition on mechanical and magnetic properties of Mn-rich Ni–Mn–Ga ferromagnetic shape memory alloys

Abstract

The effects of partial substitution of rare earth Dy for Ga on the mechanical and magnetic properties of Mn-rich Ni50Mn29Ga21−xDyx (0≤x≤5) ferromagnetic shape memory alloys were investigated in detail. The results show that an appropriate amount of Dy addition significantly improves the mechanical properties of Ni–Mn–Ga alloy. With an increase in Dy content, the compressive strength enhances rapidly at first and then becomes stable when the Dy content is more than 1at.%. However, the compressive strain increases dramatically and reaches a maximum value with 1at.% Dy addition. Further increase in Dy content makes the compressive strain of the alloys decrease gradually. The mechanism of the improved mechanical properties is also discussed. Moreover, Dy doping changes the fracture type from intergranular fracture of Ni–Mn–Ga alloy to transgranular cleavage fracture of Ni–Mn–Ga–Dy alloys. The Curie temperature remains almost unchanged at low Dy content and subsequently decreases.