Magnetostructural transformation and magnetocaloric effect of Sn-bonded Mn0.66Fe0.34Ni0.66Fe0.34Si0.66Ge0.34 composite

Magnetostructural coupling in MnMX (M = Co or Ni, X = Si or Ge) system attracts considerable attention for the accompanied multi-magnetoresponsive effects. However, due to the large stress generated from the structural transformation, the alloys become shattered or powder-like, hindering the further investigation and their applications. The possible solution is to embed the MnMX powders into metal matrix. In this paper, we choose Mn 0.66 Fe 0.34 Ni 0.66 Fe 0.34 Si 0.66 Ge 0.34 as a representative of MnMX alloy and produce Mn 0.66 Fe 0.34 Ni 0.66 Fe 0.34 Si 0.66 Ge 0.34 /Sn composite bulk by hot pressing. The magnetostructural-coupled composites exhibit an improved rate of the transformation temperature shift by magnetic field and broadened operating temperature range. Additionally, we also propose a simple formula based on the entropy-temperature diagram to calculate the isothermal entropy change, which is consistent with the results obtained by the Maxwell relation.