Large elastocaloric effect in directionally solidified all-d-metal Heusler metamagnetic shape memory alloys
Large elastocaloric effect in directionally solidified all-d-metal Heusler metamagnetic shape memory alloys
复制标题
定向凝固全d金属Heusler变磁形状记忆合金中的大弹热效应
DOI：
10.1016/j.actamat.2020.02.045
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发表时间：
2020-04-15
期刊：
影响因子：
9.4
通讯作者：
Liu, Jian
中科院分区：
文献类型：
--
作者：
Shen, Yi;Wei, Zhiyang;Liu, Jian
基于相变材料热效应的固态冷却随着对节能和环保冷却技术需求的增加引起了相当大的关注。在此，我们系统地研究了定向凝固的Ni₃₅.₅Co₁₄.₅Mn₃₅Ti₁₅全金属赫斯勒变磁性形状记忆合金的微观结构演变、马氏体相变（MT）行为以及弹性热效应（eCE）。电子背散射衍射（EBSD）分析表明，凝固态合金中存在赫斯勒型<001>取向的树枝状晶体和贫钛的枝晶间相共存的情况。经过均匀化退火后，样品呈现出柱状形态，沿生长方向具有<105>织构的五层调制（5M）马氏体。此外，通过透射电子显微镜（TEM）还识别出了具有7M和8M结构的多调制马氏体。利用原位数字图像相关（DIC）与红外热成像相结合的独特技术，研究了马氏体相变和弹性热效应行为。Ni₃₅.₅Co₁₄.₅Mn₃₅Ti₁₅合金在承受单轴应力时，产生了11.5K的大绝热温度变化（ΔTₐd），临界应力（σₑᵣ）低至38MPa，应力滞后（Δσₕᵧ）适中为54MPa，从而导致|ΔTₐd/σₑᵣ|的值最大，为0.31K MPa⁻¹。这种改善的弹性热效应归因于取向多晶合金中相容性的增强以及多调制马氏体中低能孪晶界的高迁移率。（C）2020 Acta Materialia Inc. 由Elsevier Ltd.出版。保留所有权利。
Solid-state cooling based on the caloric effect of phase transformation materials has attracted considerable interest with the increased demand for energy-efficient and environmentally friendly cooling technologies. Here, we have systematically studied the microstructural evolution, martensitic transformation (MT) behaviors, and elastocaloric effect (eCE) of directionally solidified Ni(35)(.)(5)Co(14)(.)(5)Mn(35)Ti(15)( )all-d-metal Heusler metamagnetic shape memory alloys. Electron backscatter diffraction (EBSD) analysis revealed the coexistence of Heusler-type < 001 >-oriented dendritic crystal and Ti-poor interdendritic phase for as-solidified alloys. Upon homogenization annealing, the sample presents a columnar-like morphology with < 105 > textured five-layer-modulated (5 M) martensite along the growth direction. Besides, the multi-modulated martensite with 7 M and 8 M structures was identified by transmission electron microscopy (TEM). Using a unique technique of in situ digital image correlation (DIC) with the combination of infrared thermography, MT and eCE behaviors were studied. Ni35.5Co14.5Mn35Ti15 alloy yielded a large adiabatic temperature change (Delta T-ad) of 11.5 K with a low critical stress (sigma(cr)) of 38 MPa and a moderate stress hysteresis (Delta sigma(hy)) of 54 MPa when subjected to uniaxial stress, resulting in the largest value of vertical bar Delta T-ad/sigma(cr)vertical bar = 0.31 K MPa-1. This improved eCE is attributed to the enhanced compatibility in the oriented polycrystalline alloy and the high mobility of the low-energy twin boundary in the multi-modulated martensite. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.