Microstructure, magnetism and magnetocaloric effect of Gd3NixAl2‒x alloys

Abstract

The microstructure, magnetic and magnetocaloric properties of the Gd3NixAl2‒x (x = 0, 0.1, 0.2, 0.3) alloys were systematically studied. Three phases of Gd3Al2, GdAl and Gd2Al were observed in the Gd3Al2 alloy. The lamellar GdAl and Gd2Al phases were dispersed in the main phase of Gd3Al2 alloy, which was not conducive to the plasticity of the alloy. It was demonstrated that the introduction of a small amount of Ni changed the phase composition. The Gd3NixAl2‒x (x = 0, 0.1, 0.2, 0.3) alloys underwent second-order magnetic phase transition around their Curie temperatures (TC) of 275 K, 274.5 K, 271 K and 269.5 K, respectively. The maximum isothermal magnetic entropy changes (‒ΔSM)max were 2.95 J kg−1 K−1, 2.45 J kg−1 K−1, 2.02 J kg−1 K−1 and 1.42 J kg−1 K−1 under the magnetic field change of 0–2 T. The maximum adiabatic temperature changes (ΔTad)max were 2.74 K, 2.18 K, 1.56 K and 1.14 K for Gd3NixAl2‒x alloys with x = 0, 0.1, 0.2 and 0.3, respectively. Compared with pure Gd, the Gd3NixAl2‒x (x = 0, 0.1, 0.2, 0.3) alloys exhibited weaker comprehensive magnetocaloric effect due to the reduction of magnetization caused by the addition of a large amount of Al. However, the cheaper raw material price and relatively large magnetocaloric effect make the Gd3NixAl2‒x (x = 0, 0.1, 0.2, 0.3) alloys be the potential magnetic refrigerants at near room temperature.