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本文系统研究了富Si,Mn的FeMn(P,Si)合金的显微组织、磁性和磁热效应.利用高能球磨和固态烧结法制备了Fe_(2-x)Mn_xP_(0.4)Si_(0.6)(x=1.25,1.30,1.35,1.40,1.45和1.50)系列合金.实验结果表明,合金主要形成了Fe_2P型六角结构相,伴有少量(Mn,Fe)_3Si和(Mn,Fe)_5Si_3相的析出.合金的Curie温度(T_c)随着Mn含量的增加而逐渐降低,由x=1.25时的321 K降低到x=1.5时的266 K.随着Mn含量的增加,合金逐渐由一级磁相变过程向二级磁相变过程转变.Fe_(0.75)Mn_(1.25)P_(0.4)Si_(0.6)合金具有最大等温磁墒变(-△S_(max),在0-1.5 T磁场变化下的-△S_(max)为7.2J(kg K)~(-1).Fe_(0.7)Mn_(1.3)P_(0.4)Si_(0.6)和Fe_(0.65)Mn_(1.35)P_(0.4)Si_(0.6)合金在0-1.48 T磁场变化下的最大绝热温变(△T_(ad))为1.8 K.所有合金的热滞部低于4 K.Fe_(2-x)Mn_xP_(0.4)Si_(0.6)系列合金可作为室温磁制冷的理想候选材料.
In this paper, the microstructure, magnetism and magnetocaloric effect of FeMn (P, Si) alloys rich in Si and Mn have been studied systematically.The Fe 2-x Mn x PX 0.4 Si 0.6 Ce x = 1.25, 1.30, 1.35, 1.40, 1.45 and 1.50) .Experimental results show that the alloy mainly forms a hexagonal Fe 2 P phase with a small amount of (Mn, Fe) _3Si and (Mn, Fe) . The Curie temperature (T_c) of the alloy decreases with the increase of Mn content and decreases from 321 K at x = 1.25 to 266 K at x = 1.5. With the increase of Mn content, the alloy gradually consists of primary magnetic phase (0.75) Mn 1.25 P 0.4 Si 0.6 alloy has the maximum isothermal magnetic entropy change (- △ S max), and the magnetic field changes from 0 to 1.5 T The maximum value of ΔS max is 7.2J kg K -1 .The Fe 0.7 Mn 1.3 P 0.4 Si 0.6 and 0.65 Mn 1.35 P 0.4 Si_ (ΔT_ (ad)) of 0.6 (0.6) alloy at a magnetic field of 0-1.48 T is 1.8 K. The thermal hysteresis of all the alloys is lower than 4 K. Fe 2-x Mn x 0.4 0.4 (0.6) series alloys are ideal candidates for room temperature magnetic refrigeration.