摘要
La(Fe,Si)_(13)氢化物目前被认为是最具有应用前景的室温磁制冷材料之一,对于主动式磁蓄冷制冷机而言,理想的磁制冷工质为平行排列的片状块体。本工作在压强高达40 MPa的高压氢气气氛下烧结制备了不同颗粒尺寸的厚度为0.8 mm的片状LaFe_(11.44)Si_(1.56)氢化物块体,研究了颗粒尺寸及高压烧结时间对氢化物块体的结构及磁热效应的影响。结果表明,和母合金相比,烧结样品的α-Fe含量有明显增加,而烧结时间和颗粒尺寸对α-Fe析出没有显著影响。烧结样品的居里温度在室温以上,并且随着颗粒尺寸和烧结时间的增加而稍有增加。同时,与母合金相比,烧结块体中的磁滞显著降低,这可以归因于较小的颗粒尺寸和样品中存在大量的微观孔洞,降低了相变过程中的内应力。与颗粒尺寸为110～150μm的样品相比,颗粒尺寸小于40μm的片状块体在磁熵变几乎保持不变的基础上,磁滞显著降低35%。在0～1.5 T的外磁场下其磁熵变和体积磁熵变在345 K达到最大值8.5 J/(kg·K)和53 mJ/(cm^3·K)。
La（Fe, Si）13 hydride is regarded as one of the most promising room-temperature magnetic refrigerants. A typical active magnetic refrigerator machine requires thin plate-shaped refrigerants. In this paper, plate-shaped LaFe11.44Si1.56 hydrides with different particle sizes were prepared by sintering in a high-pressure H_2 atmosphere of 40 MPa. Influences of particle size and sintering duration on the structure and magnetocaloric effect of the hydrides were investigated. The results show that compared to the parent alloy, α-Fe content of the sintered samples is increased; particle sizes and sintering duration do not remarkably influence the precipitation of α-Fe. Curie temperature of sintered samples is above room temperature, which slightly increases upon increasing of particle size. Meanwhile hysteresis of plate-shaped LaFe11.44Si1.56 hydrides has been almost eliminated due to the small particle size and many a micropore, which reduce the internal strain during the process of the phase transitions. Compared with the sintered sample with particle size from 110 to 150 μm, the hysteresis loss of the sintered sample with particle size smaller than 40 μm is decreased by 35%, while the magnetic-entropy ΔS_m remains 8.5 J/（kg·K） almost unchanged. Thin plate-shaped LaFe11.44Si1.56 hydride with particle size smaller than 40 μm exhibits the largest magnetic-entropy change（ΔSm） is 8.5 J/（kg·K） and the largest volume magnetic-entropy change is 53 m J/（cm3·K） for a field change of 0~1.5 T at 345 K.
作者
佟永丽
郭杰
任增鑫
徐志洁
孙乃坤
Tong Yongli, Guo Jie, Ren Zengxin, Xu Zhijie, Sun Naikun(Shenyang Ligong University, Shenyang 110159, Chin)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2018年第3期954-960,共7页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51261001)
辽宁省自然科学基金项目(2013020105)
沈阳市科学计划项目(F13-316-1-39)
关键词
室温磁制冷
磁热效应
高气压
颗粒尺寸
磁滞
room temperature magnetic refrigeration
magnetocaloric effect
high pressure
particle size
magnetic hysteresis
