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使用电弧熔炼法制备了La1.1Fe11.4Si1.55Ge0.05合金。研究了用少量的Ge替代Si后,La1.1Fe11.4Si1.55Ge0.05合金的磁性和磁热效应。粉末X射线衍射结果表明:在1273K真空退火处理10d后,合金La1.1Fe11.4Si1.55Ge0.05主相为NaZn13型立方结构,存在微量的α-Fe相。热磁曲线M-T与Arrott曲线表明:在居里温度Tc=205K处发生由铁磁性(TTc)的二级磁相变。在磁场变化0～1.5T下,根据等温磁化曲线通过Maxwell关系式计算得出最大磁熵变-ΔSmmax=9J.kg-.1K-1。Ge替代Si后该合金在其居里温度Tc处-ΔSm-T曲线半高宽增大,使合金的相对制冷能力RCP(S)有所提高。
La1.1Fe11.4Si1.55Ge0.05 alloy was prepared by arc melting method. The magnetic and magnetocaloric effects of La1.1Fe11.4Si1.55Ge0.05 alloy after Si substitution with a small amount of Ge have been studied. The results of powder X-ray diffraction showed that the main phase of La1.1Fe11.4Si1.55Ge0.05 alloy was NaZn13 type cubic structure with a small amount of α-Fe phase after vacuum annealing at 1273K for 10d. The thermomagnetic curves M-T and Arrott curves show that the second-order magnetic transition from ferromagnetic (T Tc) occurs at the Curie temperature Tc = 205K. The maximum magnetic entropy change -ΔSmmax = 9J.kg-.1K-1 is calculated from the Maxwell’s relationship based on the isothermal magnetization curve at a magnetic field of 0-1.5T. After the substitution of Si for Si, the full width at half maximum of the ΔSm-T curve of the alloy increases at its Curie temperature Tc, resulting in an increase of the RCP (S) of the alloy relative cooling capacity.