Magnetostructural transformation and magnetocaloric effect of Sn-bonded Mn(0.66)Fe(0.34)Ni(0.66)Fe(0.34)Si(0.66)Ge(0.34) 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.