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用高能球磨和固态烧结法制备了Mn_(1.3)Fe_(0.7)P_(0.5)Si_(0.5-x)Sn_x(x=0、0.02、0.04,原子分数)系列合金,系统研究了Sn的加入对合金显微组织、磁性和磁热效应的影响。结果表明,所有合金中都存在少量的(Fe,Mn)_3Si相,在含Sn的合金中,Sn原子并没有进入到Fe_2P晶体结构的晶格点阵位置,而是与Mn和Fe形成了Sn_2(Mn,Fe)相。Sn的加入也使合金中形成了2种成分的(Fe,Mn)_2(P,Si)相,导致样品在升温过程中出现2次铁磁-顺磁转变,对应为2个连续磁熵变峰,从而有利于合金磁制冷温区的扩展和制冷容量的提升。Mn_(1.3)Fe_(0.7)P_(0.5)Si_(0.5)合金具有优异的室温磁热效应,1.5 T磁场变化下的最大磁熵变为12.1 J/(kg·K),最大绝热温变为2.4 K,合金的热滞为3 K,Curie温度为273 K,可作为室温磁制冷的理想候选材料。
A series of Mn_ (1.3) Fe_ (0.7) P_ (0.5) Si_ (0.5-x) Sn_x (x = 0,0.02,0.04 atomic fraction) alloys were prepared by high energy ball milling and solid state sintering. Alloy microstructure, magnetic and magnetocaloric effects. The results show that there is a small amount of (Fe, Mn) _3Si phase in all the alloys. In Sn-containing alloys, Sn atoms do not enter lattice lattice sites of Fe_2P crystal structure, but form Sn_2 (Mn, Fe) phase. The addition of Sn also resulted in the formation of two (Fe, Mn) _2 (P, Si) phases in the alloy, resulting in two ferromagnetic-paramagnetic transitions during the heating process, corresponding to two continuous magnetic entropy changes Peak, which is conducive to the expansion of the alloy magnetic refrigeration temperature range and cooling capacity. The Mn_ (1.3) Fe_ (0.7) P_ (0.5) Si_ (0.5) alloy has excellent magnetocaloric effect at room temperature. The maximum magnetic entropy changes to 12.1 J / (kg · K) at 1.5 T magnetic field and the maximum adiabatic temperature changes to 2.4 K, the alloy has a thermal hysteresis of 3 K and a Curie temperature of 273 K, which is an ideal material for magnetic refrigeration at room temperature.