Ni–Mn-based metamagnetic shape memory alloys have been proposed as potential elastocaloric refrigerants. The intrinsic brittleness of the alloys has limited their cooling application. Introducing a ...soft second phase is an effective way to reduce the brittleness. From the viewpoint of application, the effect of second phase on elastocaloric effect should be illustrated. In this paper, we have investigated the microstructure, martensitic transformation and elastocaloric effect of Ni45Mn37-xIn13Co5Crx (x=0,1 and 2) polycrystalline alloys. Single-phase and precipitates-containing microstructures are obtained for the undoped and doped alloys, respectively. The precipitates in Cr-doped alloys enhances the fracture strength but significantly hinders the martensitic transformation. Balancing the fracture strength and martensitic transformation, the Ni45Mn36In13Co5Cr alloy with small amount of precipitates along grain boundaries exhibits large cooling effects of 4–6 K in the temperature range of 317–353 K.
•Single-phase and precipitates-containing microstructures are obtained for the parent and Cr-doped alloys, respectively.•The precipitates enhance the fracture strength of the alloys but significantly hinder the martensitic transformation.•The Ni45Co5Mn36CrIn13 alloy exhibits large cooling effects of 4–6 K in the temperature range of 317–353 K.
Vulcanized natural/wastes rubber blends were prepared and their elastocaloric properties were analysed. A thermodynamic frame was used to discriminate the contributions of thermoelastic effects and ...strain induced crystallization/melting. The substitution of 20 wt% of the natural rubber matrix by waste rubber particles resulted in a maintain and even a slight improvement of heat exchanges (+10%), that we ascribed to a (i) high thermoelastic effect and a (ii) a high ability of the natural rubber matrix to crystallize due to a nucleation ability of the waste particles, both resulting from a strain amplification in the rubber phase due to undeformable carbon black aggregates in the waste particles. The materials coefficient of performance, COPmat, was estimated equal to 4.4 for the neat natural rubber and 3.8 for the blend containing 20 wt% of wastes due to larger mechanical energy originated from reinforcing effect of waste particles. Nonetheless, the elastocaloric (eC) abilities of these materials, especially their wide temperature spans (similar to those in films or polycrystals using rare earth elements) make these natural/waste rubber blends good candidates for application such as heating/cooling machines. Moreover, the partial replacement of natural rubber, a bio-source material showing risks of shortage, by industrial wastes rubber, place these blends as promising eco-friendly materials with high added value.
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•Preparation of natural rubber (NR) containing ground tire rubber particles (GTR).•NR/GTR blends show giant elastocaloric effect (eC) comparing the one in NR.•eC is ascribed to thermoelastic effects and strain induced crystallization (SIC).•eC is improved in presence of GTR particles up to a content of 20 wt.%.
The superelastic behavior and elastocaloric effect of a 001-textured Ni50Mn23Ga25Cu2 polycrystal have been investigated below room temperature (256–294 K). The adiabatic temperature change caused by ...rapid unloading of uniaxial stress reached −4.3 K at 259 K. A small stress hysteresis of 14 MPa was observed. Due to the low hysteresis energy loss (0.37 MJ m−3) stemming from the texture structure, the coefficient of performance (COPmat) of our alloy was calculated to be 18, indicating that it is a promising elastocaloric candidate for low-temperature refrigeration.
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Solid-state cooling technology has attracted great attention to replace traditional vapor-compression cooling technology due to its advantages of environmentally friendly, energy conservation, and ...high efficiency. However, the cooling performance of a single field (magnetic, stress or electric field) induced caloric effect is still insufficient. Recently, a larger multicaloric effect is expected to be achieved by the synergistic regulation of multiple fields. In this study, we choose all-d-metal Ni37Co13Mn35Ti15 alloy with magnetostructural phase transition and systematically study the multicaloric effect through the synergistic regulation of external stress and magnetic fields based on our homemade multicaloric effect testing device. The magnetic field and stress field play opposite effects on the phase transition, thus contributing contradictory caloric effect to multicaloric effect. By loading stress without magnetic field while unloading stress under magnetic field of 1.1 T, the stress hysteresis and energy hysteresis loss can be reduced by up to 45.2% and 54.8% in comparison with those obtained from a non-ideal regulation protocol. Moreover, the maximum adiabatic temperature change |ΔTad| during unloading increases by 24% from 6.3 K to 7.8 K with the application of magnetic field (1.1 T), suggesting a larger multicaloric effect than that of a single elastocaloric effect. These results prove that multi-field synergistic regulation is an effective means to enhance the multicaloric effect and reduce the hysteresis and energy loss of materials with the magnetostructural transition.
•The multicaloric effect of alloys is directly measured by a homemade device.•The caloric effects are compared under different protocols of regulation.•The adiabatic temperature change of multicaloric effect increases by 24%.•The energy loss and stress hysteresis of multicaloric effect are reduced.
Elastocaloric cooling technology based on shape memory alloys (SMAs) exploits the caloric effect generated by stress-induced phase transformation of elastocaloric materials to realize refrigeration. ...It is characterized by eco-friendliness, high efficiency and energy saving and thus has been considered as one of the most promising candidates to replace the conventional vapor-compression cooling technology. Compared with magnetocaloric, electrocaloric and barocaloric refrigeration technologies, elastocaloric cooling balances cost, refrigeration capacity and efficiency, and feasibility. The review presents an overview of elastocaloric cooling from the fundamentals to the device design. We firstly describe the thermodynamic fundamentals and the characterization methods of the elastocaloric effect. Secondly, the research progress and the challenges in NiTi-based, Cu-based, Fe-based, and ferromagnetic SMAs as elastocaloric refrigerants are summarized. Furthermore, the development and the application prospects of high-performance elastocaloric materials are proposed. Finally, the advance of elastocaloric cooling prototypes is also analyzed and discussed. This review tries to outline the open crucial questions and to provide an insight to the community for further investigations of clean elastocaloric cooling.
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In typical shape memory alloys, significant elastocaloric effects appear in association with stress-induced martensitic transformations. However, we report here that in an Fe-31.2Pd (at.%) alloy, a ...significant elastocaloric effect appears due to lattice softening, which causes a weak first-order martensitic transformation at T 0 (230K). We found that in a wide temperature range of between 175K (<T 0) and 335K (>T 0), the alloy exhibits an adiabatic temperature decrease of more than 1.5K when a compressive stress of 200MPa applied in the 001 direction is removed. The refrigeration capacity calculated in this temperature range is 5MJ/m3.
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•Reduced dimensions elastocaloric materials (i.e. films, ribbons, wires and foams) are reviewed, which are expected to potential candidates for miniaturized refrigeration.•Based on ...various properties,e.g. ∆σhys, ∆Tad/∆σcr and ∆Tad/∆εtr their elastocaloric performances (∆Tad/∆Siso) are explored.•For their commercialized application, the fatigue life and cooling efficiency (COPmat and COPmat/COPCarnot) are demonstrated.•The challenges/proposed solutions and recent achievements for micro cooling eCE demonstrators/prototypes based on small-sized eCMs are ultimately outlined.
Elastocaloric cooling technology has obtained huge attraction over vapor compression systems because it is more efficient with negligible environmental impact. The elastocaloric effect (eCE) is generally concerned with superelasticity and latent heat of shape memory alloys (SMAs), related to the martensitic transformation (MT) under uniaxial loading/unloading. There are various small-scale applications such as microelectromechanical systems, medical devices and lab-on-chip systems, where active local cooling with precise temperature control is essential for their proper functioning. To explore potential eCE for miniaturized active refrigeration, reduced dimensions SMAs (i.e. thin films, microwires, ribbons and foams) may be attractive for micro cooling devices by providing a large surface to volume ratio and thus high heat transfer capacity, low thermal hysteresis and high working frequency. Therefore, the eCE properties of the state-of-the-art reduced dimensions elastocaloric materials (eCMs) are thoroughly reviewed and comparatively discussed with their bulk counterparts. The most appropriate eCMs for miniaturized eCE refrigeration are revealed on the basis of large adiabatic temperature change (△Tad), low stress hysteresis (△σhys), high cyclic stability and large coefficient of performance of material (COPmat). The challenges and recent achievements for micro cooling eCE devices/prototypes based on small-sized eCMs are summarized.
•The doping Fe element can effectively precipitate the second phase and improve the mechanical properties.•A large adiabatic temperature changes (−9.8 K) was induced by a lower loading stress.•We ...calculated the plateau of martensitic transformation which was significantly decreased compared with undoped alloys.
The influence of the substitution of Fe on the mechanical properties and elastocaloric effect (eCE) in Ni50Mn36−xIn14Fex (x = 0.5, 1, 1.5, 2, 4, 6) ferromagnetic shape memory alloys (FMSMAs) have been investigated. The results show that mechanical properties are improved by iron doping. The fracture stress and strain of arc melting Ni50Mn34In15Fe2 alloy are 411 MPa and 10.1 %, respectively. A large adiabatic temperature change (ΔTad) of up to 9.8 K was obtained via the reverse process of compressive stress-induced martensitic transformation with a lower driving stress of 175 MPa compared to the undoped alloy (256 MPa). These results show that this approach is a practical solution to the challenge of obtaining shape memory alloys with a large elastocaloric effect.
•A monocrystalline Co49Ni21Ga30 wire was fabricated by the Taylor-Ulitovsky method.•A room-temperature eCE was achieved in the Co49Ni21Ga3 wire (ΔTad = −4.1 K).•The eCE of the wire can be maintained ...over 100 cycles with no apparent degradation.
We demonstrate appreciable room-temperature elastocaloric effect in the Co49Ni21Ga30 microwires prepared using the Taylor-Ulitovsky method. By forming an almost excellent 001B2-oriented single crystal along the wire axis, extraordinary superelasticity with low critical stress and narrow stress hysteresis was achieved. Moreover, the wire exhibits room-temperature elastocaloric effect (ΔTad = −4.1 K) with no apparent degradation for 100 cycles. Due to its easy fabrication and the small scale, the wire is of great potential for advanced applications in miniature intelligent devices requiring refrigeration. This work also paves the way for developing other high-performance shape memory wires.
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