Elastocaloric effects related to B2 R and B2 B19 ' martensite transformations in nanocrystalline Ni50.5Ti49.5 microwires
Elastocaloric effects related to B2 R and B2 B19 ' martensite transformations in nanocrystalline Ni50.5Ti49.5 microwires
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DOI：
10.1016/j.jallcom.2019.04.087
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发表时间：
2019
影响因子：
6.2
通讯作者：
Muhammad Imran
中科院分区：
文献类型：
--
作者：
Xuejie Zhu;Xuexi Zhang;Mingfang Qian;Muhammad Imran
纳米晶镍钛微线具有稳定的超弹性效应，是一种极具潜力的弹热材料。本研究采用多步冷拔法制备了直径为109 μm的纳米晶ni50.5 ti49.5微线，并研究了利用B2↔R和B2↔B19 '转化的弹性热效应。与其他弹性热材料和磁热材料相比，纳米晶微线中的这两种转变都显示出相当甚至更好的热效应。的B2↔B19”转型表现出更大的熵变感(ΔS = ∼65 J /公斤·K)在一个更广泛的操作温度窗口(Δ双胞胎= ∼90 K)相比,B2↔R过渡(ΔS = ∼18 J /公斤·KΔ双= 12 K)。然而，B2↔R转移（ΔThys<10 K）的滞回比B2↔B19 '转移（ΔThys>50 K）的滞回要小得多，因为后者的转移应变较小。因此，B2↔R传递产生的eCE具有更稳定的循环稳定性。因此，目前微导线中的B2↔R和B2↔B19′都是微型制冷领域中有希望的候选物。
Nanocrystalline NiTi microwires exhibit stable superelastic effect and are highly potential as elastocaloric materials. Here, nanocrystalline Ni50.5Ti49.5microwires of diameter 109 μm were prepared by multi-step cold-drawn and the elastocaloric effect (eCE) by taking the advantage of B2↔R and B2↔B19′ transformations have been investigated. Both transitions in the nanocrystalline microwires displayed comparable or even superior caloric effect compared to other elastocaloric and magnetocaloric materials. The B2↔B19′ transformation exhibited larger stress-induced entropy change (ΔS= ∼65 J/kg·K) within a wider operation temperature window (ΔTwin= ∼90 K) compared to B2↔R transition (ΔS= ∼18 J/kg·K withΔTwin= 12 K). However, the hysteresis for B2↔R transition (ΔThys<10 K) was much smaller than that for B2↔B19′ transition (ΔThys>50 K) thanks to the smaller transition strain in the latter case. As a result, eCE produced by B2↔R tranistion possessed a more stable cyclic stability. Therefore, both B2↔R and B2↔B19′ transitions in the present microwires are promising candidates in the micro-sized refrigeration field.