Two-way shape memory effect of polycrystalline Ni–Mn–Ga–Gd high-temperature shape memory alloys

The two-way shape memory effect (TWSME) of polycrystalline Ni54Mn25Ga21−xGdx alloys is investigated. The largest TWSME value (2.9%) without training is observed in Ni54Mn25Ga20.7Gd0.3 alloy due to a small amount of Gd(Ni,Mn)4Ga phase formation, and this value increases to 3.5% after thermomechanical training. The TWSME rapidly decreases over the first few thermal cycles, and then slowly reaches a stable value as the number of cycles increases further. Finally, a 2.5% TWSME of as-trained Ni54Mn25Ga20.7Gd0.3 alloy is obtained after 50 thermal cycles.