Systematic study of the microstructure, entropy change and adiabatic temperature change in optimized La-Fe-Si alloys
Systematic study of the microstructure, entropy change and adiabatic temperature change in optimized La-Fe-Si alloys
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DOI：
10.1016/j.actamat.2011.02.033
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发表时间：
2011-05-01
期刊：
影响因子：
9.4
通讯作者：
Gutfleisch, Oliver
中科院分区：
文献类型：
--
作者：
Liu, Jian;Krautz, Maria;Gutfleisch, Oliver
对 LaFe11.8Si1.2 和 LaFe11.6Si1.4 合金在大范围退火温度和时间下的微观结构和磁热效应进行了系统研究。为了获得纯 1:13 相和最大磁熵变，LaFe11.8Si1.2 的退火温度优化为 1373 K，LaFe11.6Si1.4 的退火温度优化为 1323 K。我们发现了共析型片晶的独特形态，这表明它是 1:13 相形成时的中间相。采用绝热温度变化 Delta T-ad 测量来直接评估磁热效应。通过施加 1.9 T 的磁场，优化退火后，LaFe11.8Si1.2 和 LaFe11.6Si1.4 在转变温度附近的 Delta T-ad 值分别为 7.3 K 和 7.0 K。通过考虑磁结构转变的部分不可逆性，还讨论了热磁滞对磁熵变和Delta T-ad的影响。 (C) 2011 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
A systematic study of the microstructure and magnetocaloric effect in LaFe11.8Si1.2 and LaFe11.6Si1.4 alloys over a large range of annealing temperatures and times has been carried out. With the aim of obtaining the pure 1:13 phase and maximum magnetic entropy change the annealing temperature was optimized at 1373 K for LaFe11.8Si1.2 and 1323 K for LaFe11.6Si1.4. We found a unique morphology of eutectoid-type lamellae, which is suggested to be an intermediate phase upon formation of the 1:13 phase. Adiabatic temperature change Delta T-ad measurements were employed to directly assess the magnetocaloric effect. By application of a magnetic field of 1.9 T large Delta T-ad values of 7.3 K and 7.0 K in the vicinity of the transition temperatures were found for LaFe11.8Si1.2 and LaFe11.6Si1.4, respectively, after optimized annealing. By considering the partial irreversibility of magnetostructural transition the influence of thermal and magnetic hysteresis on magnetic entropy change and Delta T-ad is also discussed. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.