Investigation of magnetic and magnetocaloric properties of rear earth free high-entropy alloy

We investigated a new Fe26.7Ni26.7Ga15.6Mn20Si11 high entropy alloy without the rare earth element. The structural, magnetic and magnetocaloric properties of the resulting materials studied due to the varying annealing temperature. The HEAs were successfully produced by the arc melting with suction casting method. The crystal structures characterised through multiphase Rietveld refinement of X-ray diffraction data. The crystal structure of the HEAs was found to be the body centred cubic, and the Laves phase was determined to be the C15 (Cu2Mg) type structure. Formation of BCC structure and Laves phase was found to be related to the observed magnetic properties. Due to the annealing temperature, the amount of C15 Laves phase in the alloy decreased to a minimum at a certain temperature. The density of the BCC structure in the alloy also varied with the annealing temperature, and it was found that heavy lattice distortion was affected while maintaining the base structure (BCC) while maintaining the position of each atom, it has been observed that the distances to other atoms change. Cell volumes, lattice constants and phase fractions of the samples were calculated by structural analysis. These calculations showed that cell volumes, lattice constants and phase fractions changed. The relationship between these changes and magnetic and magnetocaloric properties has been demonstrated and significant differences in magnetic properties have been found to be related to heavy lattice distortion of the produced high entropy alloy. In the magnetic measurements, the ferromagnetic to paramagnetic transition obtained in the range of 300-400 K. With the employed suction casting method; the Fe26.7Ni26.7Ga15.6Mn20Si11 HEA shows the best magnetocaloric properties such as 1.589 Jkg-1K-1 maximum magnetic entropy change (0-2 T) and 75.68 Jkg-1 refrigeration capacity after the annealing process.