Giant elastocaloric effect with wide temperature window in an Al-doped nanocrystalline Ti–Ni–Cu shape memory alloy. (15th September 2019)

• Record Type: Journal Article
• Authors: Chen, Hong; Xiao, Fei; Liang, Xiao; Li, Zhenxing; Li, Zhu; Jin, Xuejun; Fukuda, Takashi
• Is Part Of: Acta materialia. Volume 177(2019)
• Page Start: 169
• Page End: 177
• Publication Date: 2019-09-15
• Subjects: Specific heat -- Ti–Ni -- Shape memory alloy -- Martensitic transformation -- Elastocaloric effect; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.07.033
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Ti–Ni based shape memory alloys are promising elastocaloric materials for solid-state refrigeration. In this paper, we made a comprehensive study on elastocaloric effect of a nanocrystalline Ti–44Ni–5Cu–1Al (at%) alloy exhibiting successive B2–B19–B19′ transformation. The maximum adiabatic temperature decrease by stress removal from 600 MPa is Δ T adi ∼25 K with a small temperature distribution of ∼0.5 K. The value of Δ T adi is consistent with that calculated from strain-temperature relation. The effective working temperature window is ∼55 K, resulting in a high refrigeration capacity of RC = 4.2 kJ/kg. Material coefficient of performance reaches COP ∼9.6 when an Otto cycle is considered. The middle eigenvalue of the transformation matrix is λ2 ∼ 0.99, implying high lattice compatibility between the parent and martensite phases. These properties are related to the diffuse nature of successive B2–B19–B19' martensitic transformation of this alloy. Graphical abstract: Image 1