Structure and magnetocaloric effect of La0.7Ce0.3(Fe0.92Co0.08)(11.4)Si-1.6 bulk alloy prepared by powder metallurgy

摘要

La0.7Ce0.3(Fe0.92Co0.08)(11.4)Si-1.6 ingot was prepared by arc melting furnace in argon atmosphere, and the starting powders was prepared from the stoichiometric melt spun ribbons by manually grinding. Bulk samples have been prepared by powder metallurgy (PM) without sintering aid from the starting powders. After sintering at 1000 degrees for 3 h under argon atmosphere, the samples achieve densities of about 7.05 g/cm(3). The structure and magnetocaloric effect of the bulk sample were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and physical property measurement system (PPMS-9). The results showed that the La0.7Ce0.3(Fe0.92Co0.08)(11.4)Si-1.6 bulk alloy consists of a dominant NaZn13-type 1:13 phase, some alpha-Fe(Si) and La-rich (LaFeSi) impurity phases, which exhibits a second-order magnetic phase transition from ferromagnetism to paramagnetism in the vicinity of Curie temperature (T-C). The maximum magnetic entropy changes occurring near its T-C are 4.1 and 8.3 J/kg K under the applied field change of 2T and 5T, respectively, which is comparable to that of Gd, suggesting that the La(0.7)Ce0.3(Fe0.92Co0.08)(11.4)Si(1.)6 bulk alloy is promising to be a low-cost, high efficiency magnetic refrigeration material at room temperature. (C) 2016 Elsevier B.V. All rights reserved.