Elastocaloric Effect Research Articles

Temperature-field history dependence of the elastocaloric effect for a strain glass alloy

• The elastocaloric effect appears in a wide temperature range for a strain glass alloy. • An inverse elastocaloric effect is observed in the strain glass alloy with history of zero-field cooling. • The temperature-history dependence of elastocaloric effect can be attributed to the slow dynamics of strain nanodomains in response to the external stress. The singular change of the order parameter at the first order martensitic transformation (MT) temperature restricts the caloric response to a narrow temperature range. Here the MT is tuned into a sluggish strain glass transition by defect doping and a large elastocaloric effect appears in a wide temperature range. Moreover, an inverse elastocaloric effect is observed in the strain glass alloy with history of zero-field cooling and is attributed to the slow dynamics of the nanodomains in response to the external stress. This study offers a design recipe to expand the temperature range for good elastocaloric effect.

Refrigeration performance and the elastocaloric effect in natural and synthetic rubbers

Elastocaloric cooling, also known as thermoelastic cooling, has been identified as a promising alternative to current state-of-the-art vapour compression cooling systems which tend to use environmentally unfriendly refrigerants. In this study, five different types of rubbers including natural rubber, silicone rubber, cis-butadiene rubber, styrene-butadiene rubber and chlorosulfonated polyethylene were investigated as working materials for thermoelastic cooling applications. A setup and protocol was developed to investigate and quantify the cooling effect of the rubbers during stretching and releasing cycles. The results show that for all five rubbers, the mechanical response of the stress–strain curve depends on the maximum loading. This is previously studied and named as Mullins effect. Such effect was negated after nine cycles of loading andunloading. The Coefficient Of Performance (COP) for the studied materials were quantified to compared to the performance of the investigated working materials. The natural rubber was found to be the working material with the best performance worth further exploration with a COP of more than 2. The cycle analysis of this material shows that the temperature difference of such system is around 7 K which shows a great potential for applications in cooling systems.

Recent Progress in Crystallographic Characterization, Magnetoresponsive and Elastocaloric Effects of Ni-Mn-In-Based Heusler Alloys—A Review

Ni-Mn-In-based magnetic shape memory alloys have promising applications in numerous state-of-the-art technologies, such as solid-state refrigeration and smart sensing, resulting from the magnetic field-induced inverse martensitic transformation. This paper aims at presenting a comprehensive review of the recent research progress of Ni-Mn-In-based alloys. First, the crystallographic characterization of these compounds that strongly affects functional behaviors, including the crystal structure of modulated martensite, the self-organization of martensite variants and the strain path during martensitic transformation, are reviewed. Second, the current research progress in functional behaviors, including magnetic shape memory, magnetocaloric and elastocaloric effects, are summarized. Finally, the main bottlenecks hindering the technical development and some possible solutions to overcome these difficulties are discussed. This review is expected to provide some useful insights for the design of novel advanced magnetic shape memory alloys.

Irradiation engineered lattice distortion in Ti-Ni shape memory alloy achieving enhanced elastocaloric effect

Large lattice distortion is the design idea to obtain a high elastocaloric effect of shape memory alloys. In the present work, a new method of He ion irradiation is used to obtain a large lattice distortion, resulting in a 6.5 K of adiabatic temperature in Ti-Ni microwires, compared to the 2.9 K of the unirradiated sample. In addition, the isothermal entropy change is 68 J/kg·K at 293 K, which is twice as high as that of unirradiated alternatives. The microwires have a larger unit cell lattice distortion after irradiation across the stress-induced martensite transformation, therefore, the irradiated sample has a larger lattice entropy change, resulting in the improvement of the phase transformation entropy change. This is the main reason that the elastocaloric effect of Ti-Ni shape memory microwires is significantly improved after He ion irradiation. This method will provide a new idea for the design of colossal elastocaloric effect materials and provide the possibility for the application of solid-state refrigeration.

Enhanced elastocaloric stability in NiTi alloys under shear stress

Significant elastocaloric effects (eCE) generated from stress-induced B2↔B19’ transition under axial load in NiTi shape memory alloys have already been proved. However, the huge hysteresis of B2↔B19’ transition directly leads to severe functional fatigue, which restricts its practical application. Here, we prepared linear NiTi spring using Ni50.8Ti49.2 wire with diameter of 300 μm aiming at converting normal stress into shear stress considering the fact that martensitic transition is achieved by shear deformation. An isothermal entropy change of ∼41 J/kg·K as well as an adiabatic temperature decrease of −16.8 K have been obtained in present spring. Furthermore, no significant degradation of elastocaloric strength emerged after 254 cycles, while only ∼2.5 K temperature degradation after 1505 cycles. Such superior stability of elastocaloric effect was mainly attributed to pure shear stress condition and gradient martensitic transition (MT) on the wire cross-section during a superelasticity cycle, which effectively reduced transition actuation load and avoided adverse factors under normal stress condition. Therefore, our spring allows for not only stable and huge caloric effect but also fast cycle frequency, thus, being attractive for micro-cooling devices or heating pumps.

Large Elastocaloric Effect in Fe‐Doped Co–Fe–V–Ga Shape Memory Alloys

Herein, the impact of Fe substitution for Co on martensitic transformation (MT), crystal structure, elastocaloric effect (eCE), and mechanical characteristics in Co51V34Ga15 shape memory alloys (SMAs) is systematically investigated. The temperatures of MT are found to be properly adjusted by varying the Fe content in Co51−xFexV34Ga15 (x = 0, 0.3, and 0.6) alloys, shifting toward the lower values as the Fe concentration increases. Furthermore, alloying with Fe is shown to significantly improve the eCE and superelastic properties of these alloys. Under the uniaxial stress of 600 MPa, the Co50.7Fe0.3V34Ga15 alloy exhibits a significant adiabatic temperature drop of −9.5 K under adiabatic cooling conditions. Moreover, it demonstrates good stability during the cycling test with a stable temperature change of −6.6 K remaining nearly constant after 420 cycles under 500 MPa. Additionally, a maximum compressive strength of approximately 1500 MPa is achieved in the Co50.7Fe0.3V34Ga15 alloy, which makes it the promising candidate for multifunctional materials.

Elastocaloric and Magnetocaloric Effects Linked to the Martensitic Transformation in Bulk Ni55Fe11Mn7Ga27 Alloys Produced by Arc Melting and Spark Plasma Sintering

The investigation of caloric effects linked to first-order structural transitions in Heusler-type alloys has become a subject of considerable current interest due to their potential utilization as refrigerants in solid-state cooling devices. This study is mainly motivated by the possibility of developing refrigeration devices of improved energy efficiency with a reduced environmental impact. We produced partially textured and isotropic bulk samples of the Heusler-type magnetic shape memory alloy Ni55Fe11Mn7Ga27 by arc melting and spark plasma sintering (SPS), respectively. Their structural, microstructural, and phase transition characteristics and magnetocaloric and elastocaloric effects, associated with first-order martensitic transformation (MT), were studied. The elemental chemical compositions of both samples were close to nominal, and a martensitic-like structural transformation appeared around room temperature with similar starting and finishing structural transition temperatures. At room temperature, austenite exhibited a highly ordered L21-type crystal structure. The partial grain orientation and isotropic nature of the arc-melted and SPS samples, respectively, were revealed by X-ray diffraction and SEM observations of the microstructure. For the arc-melted sample, austenite grains preferentially grew in the (100) direction parallel to the thermal gradient during solidification. The favorable effect of the texture on the elastocaloric response was demonstrated. Finally, due to its partial grain orientation, the arc-melted bulk sample showed superior values of maximum magnetic entropy change (|ΔSM|max = 18.6 Jkg−1K−1 at 5 T) and elastocaloric adiabatic temperature change (|ΔTadme|max = 2.4 K at 120 MPa) to those measured for the SPS sample (|ΔSM|max = 8.5 Jkg−1K−1 and (|ΔTadme|max = 0.8 K).

Combining magnetocaloric and elastocaloric effects to achieve a broad refrigeration temperature region in Ni43Mn41Co5Sn11 alloy

Solid state refrigeration is promising to replace the traditional vapor compression refrigeration technology because of the environment friendliness and energy saving. The application of solid state refrigeration requires the refrigerants possess not only favorable caloric effects but also wide refrigeration temperature region. However, the narrow working temperature region is a bottleneck problem for this technology. In this paper, we propose a method by combining the magnetocaloric and elastocaloric effects in one refrigerant to solve this problem. The ferromagnetic shape memory Ni43Mn41Co5Sn11 alloy exhibits large magnetocaloric effect across martensitic transformation and elastocaloric effect above martensitic transformation temperature simultaneously. By combining the successive caloric effects at adjacent temperature region, a broad refrigeration temperature region from 250 to 355 K can be achieved. This work indicates the combination of different caloric effects would be an effective way to widen refrigeration temperature region.

Fast Evaluation and Comparison of the Energy Performances of Elastomers from Relative Energy Stored Identification under Mechanical Loadings.

The way in which elastomers use mechanical energy to deform provides information about their mechanical performance in situations that require substantial characterization in terms of test time and cost. This is especially true since it is usually necessary to explore many chemical compositions to obtain the most relevant one. This paper presents a simple and fast approach to characterizing the mechanical and energy behavior of elastomers, that is, how they use the mechanical energy brought to them. The methodology consists of performing one uniaxial cyclic tensile test with a simultaneous temperature measurement. The temperature measurement at the specimen surface is processed with the heat diffusion equation to reconstruct the heat source fields, which in fact amounts to surface calorimetry. Then, the part of the energy involved in the mechanical hysteresis loop that is not converted into heat can be identified and a quantity is introduced for evaluating the energy performance of the materials. This quantity is defined as an energy ratio and assesses the ability of the material to store and release a certain amount of mechanical energy through reversible microstructure changes. Therefore, it quantifies the relative energy that is not used to damage the material, for example to propagate cracks, and that is not dissipated as heat. In this paper, different crystallizable materials have been considered, filled and unfilled. This approach opens many perspectives to discriminate, in an accelerated way, the factors affecting these energetic performances of elastomers, at the first order are obviously the formulation, the aging and the mechanical loading. In addition, such an approach is well adapted to better characterize the elastocaloric effects in elastomeric materials.

Solid-state cooling by elastocaloric polymer with uniform chain-lengths

Although the elastocaloric effect was found in natural rubber as early as 160 years ago, commercial elastocaloric refrigeration based on polymer elastomers has stagnated owing to their deficient elastocaloric effects and large extension ratios. Herein, we demonstrate that polymer elastomers with uniform molecular chain-lengths exhibit enormous elastocaloric effects through reversible conformational changes. An adiabatic temperature change of −15.3 K and an isothermal entropy change of 145 J kg−1 K−1, obtained from poly(styrene-b-ethylene-co-butylene-b-styrene) near room temperature, exceed those of previously reported elastocaloric polymers. A rotary-motion cooling device is tailored to high-strains characteristics of rubbers, which effectively discharges the cooling energy of polymer elastomers. Our work provides a strategy for the enhancement of elastocaloric effects and could promote the commercialization of solid-state cooling devices based on polymer elastomers.

The Development of an Experimental Prototype for Cooling the Electronic Circuits Based on Elastocaloric Effect: A Comparison between Different Configurations

The Development of an Experimental Prototype for Cooling the Electronic Circuits Based on Elastocaloric Effect: A Comparison between Different Configurations

Improvement of Mechanical Properties and Elastocaloric Effect in Ag Doped Ni-Mn-In Magnetic Shape Memory Alloys

Improvement of Mechanical Properties and Elastocaloric Effect in Ag Doped Ni-Mn-In Magnetic Shape Memory Alloys

Enhanced Cyclability of Superelasticity and Elastocaloric Effect in Cu and B Co-Doped Co-Ni-Ga Shape Memory Alloys

Enhanced Cyclability of Superelasticity and Elastocaloric Effect in Cu and B Co-Doped Co-Ni-Ga Shape Memory Alloys

Multicalorics --- new materials for energy and straintronics (R e v i e w)

The terms "multicaloric effect" and "multicaloric" are relatively new concepts and combine the phenomena and materials associated with the coexistence of conventional caloric effects under the action of external forces of various nature (magnetic field, electric field, mechanical action). Nowadays, caloric materials remain in the focus of attention of researchers, and approaches based on the use of the multicaloric effect are considered as one of the ways to improve the efficiency of conventional solid-state cooling systems. Of particular interest from a fundamental point of view are the cross effects observed under the combined external stimulus, as well as the nature of the relationship between magnetic, electrical, thermophysical properties and structure under such actions. In this review, the theoretical foundations of the multicaloric effect are considered and an attempt is made to systematize multicaloric materials. Applied aspects of multicalorics are considered separately, and various experimental approaches to the study of their properties are presented. The presented review will be of interest to a wide range of specialists involved in the study of materials with caloric effects (magnetocaloric, electrocaloric, mechanocaloric), as well as those who are searching for new functional materials. Keywords: magnetocaloric effect, electrocaloric effect, elastocaloric effect, barocaloric effect, multicaloric effect, multiferroics, multicalorics, magnetoelectric composites.

Enhancing Elastocaloric Strength by Combining Positive and Negative Elastocaloric Effects

Enhancing Elastocaloric Strength by Combining Positive and Negative Elastocaloric Effects

Elastocaloric Effect Characterization of a NiTi Tube to be Applied in a Compressive Cooling Device

Elastocaloric Effect Characterization of a NiTi Tube to be Applied in a Compressive Cooling Device

The Finding of Elastocaloric Effect in the Lightweight Shape Memory Mg-Sc Alloy

The Finding of Elastocaloric Effect in the Lightweight Shape Memory Mg-Sc Alloy

Giant Enhancement of Elastocaloric Effect by Introducing Holes

Giant Enhancement of Elastocaloric Effect by Introducing Holes

Investigation of the Elastocaloric Effect in Laser Powder Bed Fusion Niti Porous Structures

Investigation of the Elastocaloric Effect in Laser Powder Bed Fusion Niti Porous Structures

Toward tunable mechanical behavior and enhanced elastocaloric effect in NiTi alloy by gradient structure

Tailoring properties of engineering materials to meet various application requirements is a long-standing challenge in materials science. Here, we demonstrate an unprecedented strategy to achieve highly tunable mechanical behavior and significantly enhanced elastocaloric effect in superelastic NiTi via gradient structure fabricated by laser surface annealing on a severely deformed matrix. The gradient-structured (GS) NiTi sheet is characterized by a nanocrystalline core sandwiched between two coarse-grained layers with grain-size gradients enabled by progressive annealing within the thickness due to the natural degradation of heat penetration. Tailorable martensitic transformation characteristics, which gradually change from a uniform mode with quasi-linear stress-strain response to a nucleation and growth mode with plateau-type superelasticity, are readily realized through tuning the grain-size gradient. Furthermore, the GS NiTi exhibits more than 50% and 130% improvement in elastocaloric cooling capacity and efficiency compared to traditional nanocrystalline and coarse-grained NiTi with homogeneous microstructures, respectively. Such significant performance breakthroughs are attributed to the strong synergetic strengthening between fine and coarse grains in the GS NiTi, which cannot be offered by the freestanding components. The unique strengthening mechanism is activated, even in the absence of plastic deformation, by the high mechanical incompatibility among heterogeneous domains and the resultant pronounced strain gradient accommodated by martensite variants. The work opens a novel avenue for fabricating bulk GS materials with desired mechanical properties and inspires the microstructure optimization in a wide range of ferroelastic materials for giant caloric effects.