摘要
以工业生产高纯铁粉、硅粉以及LaFeSi合金粉为原料,采用粉末冶金法制备了非正分La1+xFe11.5Si1.5(x=0, 0.05, 0.15, 0.25, 0.35)块体磁制冷材料,并对其物相结构和磁性能进行了研究。结果表明,采用粉末冶金法制备的合金相比传统制备工艺下合金的成相时间明显缩短,在1353 K×3 d热处理条件下,非正分La1+xFe11.5Si1.5(x=0, 0.05, 0.15, 0.25, 0.35)材料有大量1∶13相形成。La过量值对烧结样品的物相结构及磁性能有直接影响,当x的值由0增加到0.35时,烧结样品的居里温度呈下降趋势,由228 K降低为208 K,而且样品的相变类型也逐渐由二级相变转变为一级相变。烧结样品的磁熵变及有效制冷能力则随着La过量值的增加呈现先增后降的趋势, 0~2 T下磁熵变由x=0时的5.4 J·kg^-1·K^-1增加到x=0.25时的16.4 J·kg^-1·K^-1,有效制冷能力由x=0时125.82 J·kg^-1升高至x=0.25时145.95 J·kg^-1。随着La过量值进一步增加到x=0.35, 2 T下磁熵变降低为15.7 J·kg^-1·K^-1,有效制冷能力下降为130.31 J·kg^-1。
High purity iron powder, silicon powder and LaFeSi alloy powder were used as raw materials to prepare off-stoichiometric La1+xFe11.5Si1.5(x=0, 0.05, 0.15, 0.25, 0.35) bulk material by powder metallurgy method. The influence of La excess value x on the phase formation and magnetic properties of the sintered body was studied. The results showed that the sintering time for the formation of the 1∶13 phase was significantly shortened compared to that of the traditional preparation technology. A large quantity of 1∶13 phase was formed as the matrix phase when sintered at 1353 K for 3 days. Meanwhile, the La excess value had a direct influence on magnetic properties of the sintered samples. When x value increased from 0 to 0.35, the Curie temperature decreased from 228 to 208 K, and the type of magnetic transition changed from the second order to the first order. As the La excess value increased, magnetic entropy change and the corresponding refrigeration capacity first increased and then reduced. The magnetic entropy change at 2 T increased from 5.4 J·kg^-1·K^-1(x=0) to 16.4 J·kg^-1·K^-1(x=0.25), and then decreased to 15.7 J·kg^-1·K^-1(x=0.35). While the refrigeration capacity first increased from 125.82 J·kg^-1(x=0) to 145.95 J·kg^-1(x=0.25) and decreased to 130.31 J·kg^-1(x=0.35).
作者
王蕾
叶荣昌
刘晓霞
李金兰
刘鹏举
龙毅
Wang Lei;Ye Rongchang;Liu Xiaoxia;Li Jinlan;Liu Pengju;Long Yi(School of Material Science and Engineering, University of Science and Technology Beijing, Beying 100083, China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2019年第7期774-778,共5页
Chinese Journal of Rare Metals
基金
基于材料基因工程的高性能稀土磁制冷材料研究项目(2017YFB0702704)资助
