Influence of γ phase on the magnetostructural transition and magnetocaloric properties of Ni38Co12Mn41Sn9 melt-spun ribbons

In the present work, Ni38Co12Mn41Sn9 melt-spun ribbons were annealed under different conditions to make samples free of secondary & gamma; phase precipitates or get them with various average grain sizes. A comparative study was carried out to demonstrate how & gamma; phase formation affects the martensitic transformation (MT) and the magnetocaloric properties linked to the first-order phase transition. The & gamma; phase significantly reduces the structural transformation temperatures, while slightly increases the thermal hysteresis. The & gamma; phase also de-creases the maximum entropy change (|& UDelta;S|max) and the effect is more significant for smaller & gamma; phase precipitates. As compared with those with coarse & gamma; phase grains, the ribbons containing smaller ones possess a lower |& UDelta;S|max but a smaller maximum magnetic hysteresis loss.

Automated summary

In this study, Ni38Co12Mn41Sn9 melt-spun ribbons were annealed under different conditions to obtain samples without secondary phase precipitates or with various average grain sizes. A comparative study was conducted to investigate the effect of secondary phase formation on the martensitic transformation and magnetocaloric properties. The presence of secondary phase significantly reduces the structural transformation temperatures and decreases the maximum entropy change, with a more pronounced effect for smaller secondary phase precipitates. Ribbons with smaller secondary phase grains exhibit lower maximum entropy change but smaller magnetic hysteresis loss compared to those with coarse secondary phase grains.