Study Of Near-room Temperature Magnetic Refrigerant Materials Of Lafe_11.6si_1.4b_x Compounds

The low Si content La(Fe,Si)₁₃ compounds with the giant magnetocaloric effect may be potentially useful for magnetic refrigeration.However,the La(Fe,Si)₁₃ compounds existence of the difficulty of synthesis and the elimination of a-Fe.This paper studied B influence on the microstructure,crystal structure,magnetic properties and magnetocaloric effect of LaFe_11.6Si_1.4B_x(x=0,0.2,0.5,0.7,1.0) compounds.The main results are as follows:The section of the ingots of LaFe_11.6Si_1.4B_x(x=0.2,0.5,0.7,1.0) have not grave ingredient segregation and the grain size were refined compare with LaFe_11.6Si_1.4.In addition,the ingots and melt-spun ribbons also appeared a small amount of 1:13 phase.The melt-spun ribbons can obtained single cubic NaZn₁₃ type structure,none remnant a-Fe,in short time after annealing in quantitative B.With the increase of B content,the saturated magnetization Ms decrease slightly and the Curie temperature rise slightly.The low B content compounds present a thermal induced first-order magnetic phase transition(FOT) at the Curie temperature and a field-induced itinerant electron metamagnetic transition(IEMT) at higher temperature.A simultaneous giantmagnetic entropy change |△S_m| is found in these compounds.But FOT and IEMT are weakened and gradually disappear in high B content compounds.The maximum value of magnetic entropy change |△S_m|_max=12.3J/kg·K near its curie temperature in LaFe_11.6Si_1.4B_0.5.was much larger than that of Gd (2.8J/kg·K) under a magnetic field change of 0-1T.The large |△S_m|_max under a low magnetic field and a low cost due to the 80wt.% Fe used in theLaFe_11.6Si_1.4B_0.5compound,make the compound be promising for use as magnetic refrigerant materials in corresponding temperature range.A kind of intermittent rotary active magnetic regenerator was designed.The configuration has the characteristics of rotary-reciprocating movement.The cost can be significantly decreased due to the simple structure,less heat loss and more refrigeration efficient.