A high-temperature coupling of martensitic and magnetic transformations and magnetic entropy change in Ni–Fe–Ga–Co alloys

A coupling of martensitic and magnetic transformations at ∼90 °C is found in Ni52Fe17Ga27Co4 alloy. Ageing at 300 or 400 °C has a weak effect on transformation temperatures, but significantly increases the martensitic transformation interval and hysteresis, as well as the temperature hysteresis of magnetization. Magnetic entropy changes are investigated in samples with well-coupled magnetostructural transitions. Ageing at 500 °C causes the formation of γ phase precipitates.