Orientation dependent cyclic stability of the elastocaloric effect in textured Ni-Mn-Ga alloys

Longsha Wei,Jian Liu,Lin Geng,Xuexi Zhang

doi:10.1063/1.5028212

Longsha Wei, Jian Liu + Show 2 more

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https://doi.org/10.1063/1.5028212

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Abstract

High-performance elastocaloric materials require a large reversible elastocaloric effect and long life cyclic stability. Here, we fabricated textured polycrystalline Ni50.4Mn27.3Ga22.3 alloys by cost-effective casting method to create a &lt;001&gt; texture. A strong correlation between the cyclic stability and the crystal orientation was demonstrated. A large reversible adiabatic temperature change ΔT ∼6 K was obtained when the external stress was applied parallel to &lt;001&gt; direction. However, the ΔT decreased rapidly after 50 cycles, showing an unstable elastocaloric effect (eCE). On the other hand, when the external stress was applied perpendicular to &lt;001&gt;, the adiabatic ΔT was smaller ∼4 K, but was stable over 100 cycles. This significantly enhanced eCE stability was related to the high yield strength, low transformation strain and much higher crack initiation-propagation resistances perpendicular to &lt;001&gt; direction. This study provides a feasible strategy for optimizing the eCE property by creation of the texture structure in polycrystalline Ni-Mn-Ga and Ni-Mn-X (X= In, Sn, Sb) alloys.

Highlights

The solid-state refrigeration based on the elastocaloric effect has been emerging as a promising candidate technique for the conventional vapor-compression refrigeration.[1]
Improvement of the martensite transformation (MT) reversibility may be realized by tuning the geometric compatibility between A/M interface.[15,16]
In Ni-Mn-Ga alloys, the austenite↔5M martensite exhibited the most promising elastocaloric effect (eCE) due to the low superelastic critical stress and small transition strain,[19] which benefit for a long fatigue life

Summary

Introduction

The solid-state refrigeration based on the elastocaloric effect (eCE) has been emerging as a promising candidate technique for the conventional vapor-compression refrigeration.[1]. B2-R is smaller than that of B2-B19’, implying a better elastocaloric reversibility during B2-R cycling.[18] In Ni-Mn-Ga alloys, the austenite↔5M martensite exhibited the most promising eCE due to the low superelastic critical stress and small transition strain,[19] which benefit for a long fatigue life.

Results

Conclusion