Experimental Study of Magnetocaloric Effect in Ni-Fe-Mn-Ga and Ni-Co-Mn-Ga Heusler Alloys

Abstract

In this work we experimentally studied the MCE in the Heusler alloys Ni 2.19-x Fe x Mn 0.81 Ga (x = 0.01, 0.02, 0.03, 0.04) and Ni 2.16-x Co x Mn 0.84 Ga (x = 0.03, 0.06, 0.09). Magnetocaloric effect was measured by the direct method using the installation from the company AMT&C. The temperature dependencies of ∆T ad for the magnetic field change ∆H = 2 T were measured. The phase transition temperatures were determined from temperature dependencies of low field magnetization measured by original setup using Hall effect. Studies have shown that replacement of the Ni atoms with the iron atoms slightly reduces the temperature magnetostructural transition for x = 0.01,0.02, and starting with x = 0.03, magnetic and structural transitions occur separately and a further increase in iron concentration leads to the Curie temperature increase, while the temperature martensitic transformation decreases. When replacing the Ni atoms with the Co atoms of the martensitic transformation temperature and Curie temperature increase.