Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

Abstract

This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu 68 Al 16 Zn 16 (CuAlZn) and Cu 73 Al 15 Mn 12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s −1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (Δ T ad ) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hysteresis at each strain were compared. The stress at the maximum recoverable strain of 4.0% for CuAlMn was 120 MPa, which is 70% smaller than that of CuAlZn. A smaller hysteresis for the CuAlMn alloy was also obtained, about 70% less compared with the CuAlZn alloy. The latent heat, determined by differential scanning calorimetry, was 4.3 J g −1 for the CuAlZn alloy and 5.0 J g −1 for the CuAlMn alloy. Potential coefficients of performance (COP mat ) for these two alloys were calculated based on their physical properties of measured latent heat and hysteresis, and a COP mat of approximately 13.3 for CuAlMn was obtained. This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’.

Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat

“…The cooling effect with adiabatic change in temperature was demonstrated in NiTi and NiTiCu alloys in 2012. [6,7] The efforts to explore new elastocaloric materials have gone from binary TiNi alloys [6][7][8] to ternary and quaternary TiNi-based alloys, [7,[9][10][11][12][13] Cu-based alloys, [14][15][16] and magnetic alloys. [17][18][19][20][21][22] At the same time, there have also been development of prototypes of elastocaloric systems and devices based on compressive thermoelastic tubes [23,24], tensile sheet/ribbons, [25] and bending films.…”

Giant elastocaloric effect covering wide temperature range in columnar-grained Cu71.5Al17.5Mn11 shape memory alloy

“…4(a) shows the stress-strain curves upon loading at different testing temperatures of the as-aged sample and it is important to note that the large ∆T exp was achieved at considerably low applying stresses. For example, the critical stress for inducing martensitic transformation was 83 MPa at 315 K in the as-aged sample, the maximum stress σ max was 127 MPa, and the corresponding specific elastocaloric ability ∆T exp /σ max was then calculated to be 100.8 K/GPa, which is much higher than that of 22.7 K/GPa in Ni-Ti 7 and other elastocaloric alloys, 8,10,11,18,21,[23][24][25][26][27] as shown in Fig. 4(b).…”

“…A single-crystalline Cu 72 Al 17 Mn 11 alloy was recently found to have a directly measured adiabatic temperature change of 3.9 K under compression, which is, however, not considerably large and is far away from the predicted value of 11.6 K due to the small achieved pseudoelasticity of less than 4%. 18 In this paper, we report on the elastocaloric effect in a columnar-grained Cu 71.5 Al 17.5 Mn 11 alloy under tension.…”

Применение изотермической осадки для мегапластической деформации beta-сплавов Cu-Al-Ni

“…Их практическое использование особенно важно в медицине, авиации, космической технике, на транспорте и в строительстве, где необходима длительная высокая надежность изделий при эксплуатации в достаточно широком интервале температур подчас при их минимальных или, напротив, больших размерах и сечениях [1][2][3]. Последние годы также обращается внимание на возможность применения данных сплавов с эласто-и магнитокалорическими эффектами для твердотельных холодильников [4,5]. Вместе с тем даже среди сплавов никелида титана с рекордным комплексом физико-механических свойств детально исследованы и находят применение только их бинарные композиции в узком диапазоне легирования никелем (от 49.5 до 50.5 at.%) [1][2][3].…”

“…Но очевидно, что для широкого применения необходимы объемные материалы с ЭПФ в обычном поликристаллическом состоянии. Однако в данных сплавах традиционные термические или термомеханические обработки не могут обеспечить требуемые физико-механические и эксплуатационные параметры [1,[5][6][7][8][9][10][11][12][13]. Низкая пластичность в поликристаллическом [1][2][3] и даже в монокристаллическом [3,14] состоянии не позволяют практически реализовать ЭПФ, присущие монокристаллам большинства цветных сплавов, включая и β-сплавы на основе меди [2].…”