Influence of the substitution of Ni for Fe on the microstructure evolution and magnetic phase transition in La(Fe1 − xNix)11.5Si1.5 compounds

The influence of Ni substitution on the microstructure evolution and magnetic phase transition has been investigated in La(Fe1 − xNix)11.5Si1.5 (x = 0, 0.01, 0.02, 0.03) compounds. Results show that partial substitution of Ni for Fe in La(Fe1 − xNix)11.5Si1.5 (x = 0, 0.01, 0.02, 0.03) alloys promotes fining of the as-cast microstructure. Besides, the formation of 1:13 phase and the elimination of impurity phases is facilitated significantly when annealed at 1373 K for 5 days. Large amounts of inhomogeneities are present in the annealed LaFe11.5Si1.5 alloy. While almost single 1:13 phase is obtained in La(Fe1 − xNix)11.5Si1.5 (x = 0.02, 0.03) alloys. Moreover, the Curie temperature TC of La(Fe1 − xNix)11.5Si1.5 (x = 0, 0.01, 0.02, 0.03) compounds increase monotonously from 195 K to 219 K when Ni content x varies from 0 to 0.03.