弹热制冷是一种新型固态制冷技术,具有对环境友好和能量利用效率高等优点,有望替代传统的蒸气压缩制冷技术.实现弹热制冷应用的关键在于获得兼具大弹热效应和高循环稳定性的弹热材料作为制冷剂.Ni-Fe-Ga记忆合金是一种很有潜力的弹热材料.该合金采用常规熔炼方法易形成γ相,然而有关γ相对合金弹热性能的影响却缺乏系统和深入的研究.有鉴于此,制备了 一种含γ相的Ni53.6Fe19.3Ga27.1多晶合金,采用X射线衍射仪、透射电子显微镜、差示扫描量热仪、电子万能材料试验机以及自制的弹热效应测试系统,分析了其显微组织、力学性能和弹热性能.结果表明,Ni53.6Fe19.3Ga27.1多晶合金的基体是β相,γ相同时分布于晶粒内和晶界上,这种两相结构有助于合金获得大且稳定的弹热效应,室温绝热温变值超过-5 K.
Cycling stability of elastocaloric effect in a Ni53.6Fe19.3Ga27.1 polycrystalline alloy
Elastocaloric cooling,as a typical solid-state refrigeration technology,is recognized as an alternative to the conventional vapor compression cooling due to the advantages of being environmentally friendly and high energy utilization efficiency.The key to develop elastocaloric cooling technology is to obtain high-performance elastocaloric materials with large elastocaloric effect(eCE)and high cyclic stability as the refrigerants.Ni-Fe-Ga shape memory alloy is regarded as a kind of promising elastocaloric material.The formation of y secondary phase is inevitable using conventional melting technique,however,systematic and in-depth studies on the effect of y phase on the eCE of Ni-Fe-Ga alloys are scarce.For this purpose,Ni53.6Fe19.3Ga27.1 polycrystalline alloy is fabricated in this work and the microstructure,mechanical properties and eCE are studied by X-ray diffraction,transmission electron microscope,differential scanning calorimetry,universal testing machine,self-designed eCE experimental setup,etc.It shows that,in the present alloy,y phases are formed inside,and the grains and along the grain boundaries of βphases.Such a dual-phased structure helps to achieve a considerable eCE with high cycling stability.The value of adiabatic temperature change exceeds-5 K.
万方数据
维普
