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用电弧熔炼法制备了LaY0.1Fe11.4T0.1Si1.5(T=Cr,Mn,Fe,Co,Ni)系列合金。室温XRD分析与SEM成分分析表明,该系列合金中除存在一个明显的杂相峰(富La相,P4/nmm)和α-Fe相外,主相为NaZn13型立方相。除T=Cr外,Fe位原子替代使合金的晶格常数随着替代原子T的原子半径的减小而减小。磁性测量表明,该系列合金除T=Mn以外,随着替代原子T的原子半径减小,合金的居里温度(TC)有增加的趋势。在外磁场变化ΔB=1.5T时,利用Maxwell方程计算得出,该系列合金磁熵变最大值分别为5.1,13.0,20.7,12.7和7.4J·kg-1·K-1。由此可以看出,T=Fe时合金的磁熵变最大值最大,且该系列合金的磁熵变峰值随着外磁场增加向高温区不对称展宽;TC以上磁场引起的变磁转变是磁熵变峰值不对称展宽的原因。
LaY0.1Fe11.4T0.1Si1.5 (T = Cr, Mn, Fe, Co, Ni) series alloys were prepared by arc melting method. The results of XRD and SEM at room temperature show that the main phase is NaZn13-type cubic phase except that there is an obvious hetero-phase peak (La-rich phase, P4 / nmm) and α-Fe phase in this series of alloys. Except for T = Cr, the atomic substitution of Fe decreases the lattice constant of the alloy as the atomic radius of the substitutional atom T decreases. Magnetic measurements show that the addition of T = Mn, with the atomic radius of the alternative atom T decreases, the Curie temperature (TC) of the alloy tends to increase. When the change of external magnetic field is ΔB = 1.5T, Maxwell’s equation is used to calculate the maximum value of magnetic entropy change for the series alloy, which is 5.1, 13.0, 20.7, 12.7 and 7.4J · kg-1 · K-1, respectively. It can be seen that the maximum magnetic entropy change of alloy is the maximum at T = Fe, and the peaks of magnetic entropy change of the alloys expand asymmetrically to the high temperature region as the external magnetic field increases. The magnetic transition caused by the magnetic field above TC is magnetic The reason of asymmetric peak broadening of entropy.