Superelasticity Effect Research Articles

Anisotropic Superelastic and Shape Memory Effect of Nitinol Manufactured by Electron Beam Powder Bed Fusion

Anisotropic Superelastic and Shape Memory Effect of Nitinol Manufactured by Electron Beam Powder Bed Fusion

Strengthening of an existing RC building with superelastic SMAs

Retrofit of deteriorated Reinforced Concrete (RC) structures has been widely investigated to enhance their performance and avoid the environmental impact due to demolishing and reconstruction. As conventional design concept is oriented to a predictable, ductile behavior allowing for significant inelastic deformation, implying extensive damage of structural members and leading to costly repairs after serious earthquake incidents, smart materials occupied with an inherent re-centering ability have been investigated for retrofit applications to reduce structural damage, constituting potential candidates for innovative interventions that can improve the structural resilience under seismic actions. In this work, a RC building situated in Athens, Greece is used as a case study to evaluate the potential of Shape Memory Alloys (SMAs) in structural retrofit, exploiting their property to reset inelastic deformations by unloading exhibiting the superelastic effect. Different types of SMAs are investigated to assess the effectiveness of the proposed retrofit scheme as an alternative solution to conventional steel performing pushover and non-linear dynamic time history analysis with SeismoStruct software. Results show maximum and residual displacement reduction and provide useful information on the application of SMAs as a damage-control and cost-efficient scheme in structural retrofit with the view to deal with the issue of significant residual deformation after earthquake action.

Achieving superelastic shape recoverability in smart flexible CuAlMn metamaterials via 3D printing

Despite the remarkable advancements in the additive manufacturing of metamaterials, tradeoffs remain between functionality and mechanical performance owning to static configuration, which limits their application, particularly in areas that require efficient multifunctionality. In this paper, we present a novel approach for fabricating multifunctional smart flexible metal metamaterials using laser powder bed fusion technology. This approach enables the reversible recovery superelastic strain exceeding 20 % with a 100 % recovery rate—ten times higher than that observed in the printed alloy. This is achieved by utilising an innovative metamaterial structural design and a novel shape memory alloy powder. To achieve the aforementioned purpose, the metamaterial unit cells were initially designed to ensure flexible deformation ability with a Poisson's ratio of zero. Then, we prepared a novel shape memory alloy composition of Cu-18at%Al-l0at%Mn-0.3 at%Si, which exhibited excellent printability and adaptability within the laser powder bed fusion additive manufacturing process. Additionally, the printed SMA exhibited superelasticity, one-way and two-way shape memory effect under varying parameters. Furthermore, the combination of multifunctionality into the flexible CuAlMn metamaterials was achieved by manipulating process parameters. Remarkably, the printed metamaterial demonstrates exceptional flexibility deformation, and presents superelasticity or shape memory effect, ensuring the recovery of its original shape after experiencing deformation. This work not only demonstrates the vast potential of utilising additive manufacturing technology for fabricating functional and adaptable metal metamaterials but also presents an innovative approach for creating smart metal metamaterial.

Phase-field description of fracture in NiTi single crystals

A phase-field model for thermomechanically-induced fracture in NiTi at the single crystal level, i.e., fracture under loading paths that may take advantage of either of the functional properties of NiTi–superelasticity or shape memory effect–, is presented, formulated within the kinematically linear regime. The model accounts for reversible phase transformation from austenite to martensite habit plane variants and plastic deformation in the austenite phase. Transformation-induced plastic deformation is viewed as a mechanism for accommodation of the local deformation incompatibility at the austenite–martensite interfaces and is accounted for by introducing an interaction term in the free energy derived based on the Mori–Tanaka and Kröner micromechanical assumptions and the hypothesis of martensite instantaneous growth within austenite. Based on experimental observations suggesting that NiTi fractures in a stress-controlled manner, damage is assumed to be driven by the elastic energy, i.e., phase transformation and plastic deformation are assumed to contribute in crack formation and growth indirectly through stress redistribution. The model is restricted to quasistatic mechanical loading (no latent heat effects), thermal loading sufficiently slow with respect to the time rate of heat transfer by conduction (no thermal gradients), and a temperature range below Md, which is the temperature above which the austenite phase is stable, i.e., stress-induced martensitic transformation is suppressed. The numerical implementation of the model is based on an efficient scheme of viscous regularization in both phase transformation and plastic deformation, an explicit numerical integration via a tangent modulus method, and a staggered scheme for the coupling of the unknown fields. The model is shown able to capture transformation-induced toughening, i.e., stable crack advance attributed to the shielding effect of inelastic deformation left in the wake of the growing crack under nominal isothermal loading, actuation-induced fracture under a constant bias load, and crystallographic dependence on crack pattern.

Functional fatigue of superelasticity and elastocaloric effect for NiTi springs

In this work, the evolutions of superelasticity (SE) and elastocaloric effect (eCE) for NiTi shape memory alloy (SMA) helical springs under cyclic deformation are investigated experimentally and theoretically. Experimental results show that the functional fatigue of SE and eCE occur simultaneously, and these phenomena aggravate significantly with the increase/decrease of the loading level/spring index. Then, a thermo-mechanically coupled constitutive model is established. Two major inelastic deformation mechanisms, martensitic transformation (MT) and transformation-induced plasticity (TRIP), are incorporated. In addition to the martensitic and austenitic phases, the martensitic influence zone is also considered in the proposed constitutive model to characterize the high local stress in the region near the austenitic-martensitic interface. To accurately describe the deformation behavior of NiTi SMA springs, an analytical model considering both the torsion and bending deformation modes is employed. Furthermore, the lumped heat transfer analysis method is adopted to derive the evolution equation for the overall temperature of the springs. Finally, to verify the rationality of the newly developed model, predicted results for the functional fatigue of SE and eCE are compared with the experimental data.

Removal mechanism of NiTi alloy by ultrasonic assisted polishing based on molecular dynamics simulation

NiTi alloy has been widely used in mechanical and electronic, aerospace, energy and transportation, petrochemical industry and various biomedicine fields due to its unique super elasticity and shape memory effect. The traditional polishing method of NiTi alloy has the problems of poor consistency of polishing quality and low efficiency, especially for some NiTi alloy with complex shapes, the traditional mechanical contact method is difficult to polish its inner surface. For some NiTi alloys prepared by additive manufacturing, due to the existence of “step effect” and “spherodizing effect”, there are unmelted powder particles on the surface, and it also needs to be polished. However, it is necessary not to destroy the original structure shape and performance, but also to achieve high efficiency, high quality and consistent polishing, so it is a technical problem. Its polishing process is still unclear, and the polishing effect needs to be improved. Therefore, in this paper, molecular dynamics method was used to study the polishing process of ultrasonic vibration diamond abrasive particles on NiTi alloy. The influences of ultrasonic vibration frequency, ultrasonic amplitude and temperature on polishing force, average friction coefficient, surface morphology, structural evolution and dislocation distribution were studied, and the microscopic material removal mechanism was revealed. The results indicate that as the ultrasonic frequency increases, the number of normal force fluctuations increases, and the elastic and plastic deformation during the scratching process also increases. With the increase of ultrasonic amplitude, the average friction coefficient decreases, and the adoption of larger vibration amplitude is conducive to the scratching process, and the average friction coefficient will increase when the temperature increases, which is not conducive to the polishing process.

Experimental study of shape memory alloy plates under cyclic tension–compression loading scenarios

Shape memory alloys (SMAs) have garnered significant attention for their potential in earthquake-resistant structures, primarily due to their superelastic effect and exceptional self-centring capabilities. However, the mechanical properties of SMA plates, especially under cyclic tension–compression loading, remain underexplored. This research aims to bridge this gap by designing and testing 33 SMA plates equipped with buckling-restrained devices. The study varied parameters such as specimen thickness (4 mm, 6 mm, and 8 mm), loading protocols (seven in total), and test temperatures (25 °C and 0 °C). The findings reveal that the stress–strain curves under cyclic tension–compression loading exhibited asymmetric characteristics. For instance, at 25℃, a 4 mm thick specimen at 4% strain had a compressive peak stress that was 22.2% higher than its tensile counterpart, and its compressive residual strain exceeded the tensile residual strain by 99.0%. Furthermore, when compared to SMA plates under cyclic tension-release loading, those under cyclic tension–compression loading had reduced tensile residual strains. At 0 °C, the peak stress saw a decrease ranging from 2.4 to 43.1%, while the residual strain surged by 11.9–591.4% compared to the tests at 25℃. This study provides novel insights into the behavior of SMA plates under varied conditions, emphasizing their potential for seismic applications.

Orientation dependence of elastocaloric effect in a Cu71.3Al17.5Mn11.2 single crystal

In this work, the orientation dependence of superelasticity and elastocaloric effect was systematically investigated in a Cu71.3Al17.5Mn11.2 single crystal, which was prepared by means of abnormal grain growth induced by cyclic heat treatment using a < 001 >A textured polycrystalline alloy as the precursor. By comparing the superelastic and elastocaloric response upon applying the compressive loading along the < 001 >A, < 110 >A and < 111 >A orientations, it was shown that the < 001 >A orientation can yield the largest transformation strain, the lowest transformation stress and the most remarkable elastocaloric response. Large stress-induced adiabatic temperature change (|ΔTad|) values of 12 K ∼ 15 K, covering a wide temperature window from 293 K to 453 K, were achieved upon removing a compressive loading of 500 MPa for the < 001 >A oriented single crystal. Moreover, favored by the relatively lower driving stress along the < 001 >A orientation, the specific adiabatic temperature variation (|ΔTad/σmax|) can be as large as 107.3 K/GPa. This work clearly demonstrates the strong influence of crystallographic orientation on the elastocaloric properties resulting from stress-induced martensitic transformation, which is expected to provide some instructions for designing high-performance elastocaloric materials.

Analyses of the sliding wear behavior of NiTi shape memory alloys fabricated by laser powder bed fusion based on orthogonal experiments

Laser powder bed fusion of NiTi (LPBF-NiTi) alloys is gaining increasing attention and applications because of its flexible design for complex structures with excellent superelasticity and shape memory effects. Their wear behavior has a strong influence on the serviceability and safety, but the effects of their usage condition on the wear behavior are not clarified clearly. In the present work, the wear resistance of LPBF-NiTi (55.4 wt%Ni) alloys against 100Cr6 steel on a ball-on-slab tribometer and its response to sliding speed, normal load and sliding time were studied through orthogonal experiments. The results confirm that the wear rate of LPBF-NiTi alloys ranges from 1.1–2.5 × 10−3 mm3/m, which is comparable to that of NiTi alloys fabricated by conventional methods. In addition, the sliding speed has the largest influence with a range of 5.1 × 10−5 mm3/Nm, followed by normal load with a range of 4.2 × 10−5 mm3/Nm. The effect of the interaction between the normal load and sliding speed is significantly greater than the effect of the sliding time. Finally, the wear mechanism of the worn surface and microstructure of the subsurface under the wear track were discussed in detail. The dominant wear modes are adhesion, abrasion and delamination.

Achieving high strength and large recoverable strain by designing honeycomb-structural dual-shape-memory-alloy composite

Developing shape memory alloys (SMAs) with high strength and large recoverable strain is meaningful to broaden their application in extreme scenarios. In this work, a dual-SMA composite with bio-spired honeycomb structure, which consists of NiTi SMA matrix and NiTiZrCu SMA reinforcement, was designed and fabricated through the combination of 3D printing and hot extrusion. The utilization of honeycomb structure ensures uniform stress transmission and reducing the likelihood of stress concentration. The resulting microstructure, martensite transformation, and superelasticity were studied systematically. The dual-SMA composite exhibited a superior superelasticity with a remarkable recoverable strain higher than 5% and good recovery rate of 96% under a high external stress of 1.4 GPa. Fundamentally, the honeycomb structure in the dual-SMA composite facilitates the occurrence of progressive phase transformation process. The large recoverable strain and good recovery rate were attributed to the coupling effect of superelasticity and linear-elasticity throughout the whole loading process, which enables the dual-SMA composite to sustainably bear the load without undergoing plastic yielding. These findings make it available for designing and fabricating SMA composites with superior performance.

Experimental, mathematical model, and simulation of a dual-system self-centering energy dissipative brace equipped with SMA and variable friction device

The application of shape memory alloy (SMA) in seismic-resistant devices has received extensive attention due to its unique superelastic and shape memory effect. The poor energy dissipative capacity, insufficient reliability, and small bearing capacity are the main challenges that hinder the application of the developed SMA braces and dampers. The new system of self-centering energy dissipative (SCED) brace was proposed, fabricated, and tested, and the numerical model was defined and verified. The dates manifest that the load-displacement curve of the new dual-system SCED brace displays a typical flag shape. The new dual-system SCED brace exhibits the desirable energy dissipative ability and self-centering capacity and the theoretical and FE model established in this research can preferably express the hysteretic performance. The FE parametric analysis shows that the SMA screw preload has a small effect on the hysteretic curve of the new system brace, but it plays a decisive role in the shape of the hysteretic curve under small deformation. Furthermore, the bearing capacity and stiffness of the dual-system SCED brace can be adjusted by designing key parameters. The research shows that the new dual-system SCED device compensates for the shortcomings of the existing SMA braces and dampers, and it is a very promising and recommended self-centering energy dissipative device to use the wedge block system as the main energy dissipative system and SMA system as the main self-centering system.

Improving the fatigue strength of superelastic NiTi by using constrained groove pressing severe plastic deformation deform 3D modeling and microstructural analysis

NiTi has wide ranges of applications in the aerospace, biomedical, automotive, and other sectors due to its superelasticity and shape memory effect smart properties. Numerical modeling is an efficient and cost-effective approach to investigate the effects of applied loads and plastic deformation processes on the mechanical properties of NiTi. The aim of this work is to apply Deform 3D modeling of constrained groove pressingsevere plastic deformation to improve the fatigue strength of superelasticNiTi by considering cantilever beam structure subjected tobending load. After applying the constrained groove pressing severeplastic deformation, the effects of deformation parameterson the fatigue strength were evaluated by comparing with theproperties of the undeformedbeam. First, to increase the resilience of NiTito fatigueloadings, the stress relief groove geometry wasdesigned by using Deform 3D software. Theeffects of deformation temperature, groove depth, and groove radius were investigated and the optimum values were selected for further analysis. The grain size of the deformed NiTispecimen was significantly reduced and the fatigue resistance was increased corresponding to the groove depth and groove radius increment. Due to constrained groove pressing severe plastic deformation, the grain refinement (15.8 nm-2.5277 μm)of NiTiwas observed at the maximum groove depth (5–6 mm). By using the Hall-Petch relations, the yield strength of NiTi was determined. As a result, the yield strength is improved by 239 % in comparison with the initial value. Furthermore, in comparison with the undeformedNiTi specimen, the fatigue strength is improved by 54.6%.

Shape Memory Alloy‐Based Seismic Retrofit of an existing URM Building

AbstractMasonry buildings constitute a considerable part of the existing building stock and are often related to significant architectural and cultural value. Empirical construction, accumulated damage, material heterogeneity and anisotropic behavior deteriorate their structural and seismic capacity, increasing thus the risk of undergoing severe damage and even collapse. To enhance these buildings' performance, various retrofit schemes have been developed and have been included in current codes and standards, mostly utilizing conventional materials and improvement of their intervention techniques. Recently, research efforts are oriented to the application of emerging metal materials with advanced properties endowed with re‐centering abilities that conventional materials lack, aiming to achieve vibration control and mitigate potential structural damage.This work investigates the use of shape memory alloys (SMAs) for the seismic protection of masonry buildings focusing on the exploitation of their superelastic effect, namely the ability to revert to their original shape after being subjected to large deformations. The research adopts a case study approach, developing an SMA based retrofit scheme to be applied to an existing listed unreinforced masonry building in Thessaloniki. For the purposes of the study, finite element modeling is performed, while response spectrum analysis is carried out to assess the effectiveness of the introduced retrofit strategy.

Healing effect of electric current treatment on superelasticity and elastocaloric effect of TiNi shape memory wire

This study investigated the healing effects of electric current treatment on Ni-rich TiNi shape memory wire after every 100 superelastic cycles. The diameter of the TiNi wire was 0.5 mm. The electric current treatment was applied without removing the wire from the tensile machine, aiming for online healing of the shape memory alloy. The electric current treatment showed an obvious healing effect, which restored the superelastic and elastocaloric properties of the functionally degraded TiNi shape memory wire. With treatment conditions of 20.4 A/mm2 and 2 min (the temperature of the wire increased up to 280 °C in 10 s), the elastocaloric temperature rise and drop of the TiNi wire recovered about 14% and 6% after 3–4 treatments, respectively, as compared with the case without any heat treatment. TEM observations indicated that the residual martensite introduced into the TiNi wire during superelastic cycles could be eliminated through the electric current treatment. Experimental results demonstrated that electric current treatment was a promising method to restore the functionality of the TiNi SMA wire after several superelastic cycles without the need to remove the wire from the apparatus, which would thus improve the performance of shape memory alloys during their long-term application.

Evaluation of the mechanical properties and clinical application of nickel-titanium shape memory alloy anal fistula clip.

The study investigates the mechanical properties of a nickel-titanium shape memory alloy anal fistula clip (NiTi-AFC), studies the surgical method of treating anal fistula, and evaluates its clinical efficacy. The anal fistula clip was formed in nickel-titanium alloy with a titanium content of 50.0%-51.8%. The mechanical properties and chemical properties were tested. A total of 31 patients with anal fistula were enrolled between 1 January 2020 and 1 January 2023. All patients underwent internal orifice closure surgery using NiTi-AFC, and anorectal magnetic resonance or ultrasound was performed before surgery and 6 months after surgery for diagnosis and evaluation. Fistula cure rates, length of stay, perianal pain, and Wexner incontinence scores were retrospectively compared between patients treated with NiTi-AFC and patients treated with other surgical methods. NiTi-AFC has a density of 6.44-6.50 g·cm-3, with a shape-restoring force of 63.8 N. The corrosion rate of NiTi-AFC in 0.05% hydrochloric acid solution at atmospheric pressure and 20°C is approximately 6.8 × 10-5 g·(m·h)-1. A total of 31 patients (male/female: 19/12, age: 43.7 ± 17.8 years) were included. Among them, 22.6% (7) had multiple anal fistula, 16.1% (5) had high anal fistula, and 48.3% (15) had perianal fistula Crohn's disease. In total, 12.9% (4/31) did not achieve primary healing, underwent fistula resection, and eventually recovered. A retrospective analysis showed that the fistula healing rate, length of stay, and anal pain of NiTi-AFC treatment were similar to those of other traditional surgeries, but the Wexner incontinence score was significantly lower. NiTi-AFC has shape memory properties, corrosion resistance, superelastic effect, and surface cell adhesion. It is applied to internal orifice closure surgery of anal fistula, with good therapeutic effect, and can protect the anal function.

Laser powder bed fusion of full martensite Cu-Al-Mn-Ti alloy with good superelasticity and shape memory effect

A copper-based shape memory alloy Cu-11.85Al-3.2Mn-0.1Ti with desirable superelasticity and shape memory effect was printed by laser powder bed fusion (LPBF), which demonstrated the feasibility of engineering applications through the deformation and recovery of complex corrugated structural components. The microstructure of LPBF-printed Cu-11.85Al-3.2Mn-0.1Ti was composed of full β1' martensite with a high density of stacking faults and twin crystals. The abnormal phase constitution of full martensite in the printed Cu-11.85Al-3.2Mn-0.1Ti is correlated to substrate preheating and thermal cycling during LPBF. The start and finish transformation temperatures of martensite (Ms and Mf) and austenite (As and Af) were 172.5 °C, 144.4 °C, 180.2 °C and 209.2 °C, respectively. The printed samples exhibited compressive strength of 1319 MPa with a compressive fracture strain of 16.1%. The printed alloy displayed remarkable superelasticity and shape memory effect. The superelastic recovery rate reached a maximum value of 87% at 6% pre-strain, corresponding to a superelastic recovery strain of 5.22%. The mechanism of superelasticity is attributed to the rubber-like deformation behavior. Moreover, the pre-strained samples demonstrated a desirable shape memory effect under the temperature stimulation, where the shape memory recovery rate of up to 100% at a pre-strain of 6%, corresponding to a shape memory recovery strain of 0.78%. The reasons for the favorable shape memory effect were: (i) the thermoelastic inversion of martensitic transformation and (ii) the precipitation of γ2(Cu9Al4) phase along the grain boundaries. As a result, these findings suggest that the LPBF technique can produce Cu-Al-Mn-Ti parts with superelasticity and good shape memory properties, which provided valuable references for printed copper-based shape memory alloys with full martensitic structures.

Shape Memory Alloys Applied to Automotive Adaptive Aerodynamics.

Shape memory alloys (SMAs) are gaining popularity in the fields of automotive and aerospace engineering due to their unique thermomechanical properties. This paper proposes a numerical implementation of a comprehensive constitutive model for simulating the thermomechanical behavior of shape memory alloys, with temperature and strain as control variables to adjust the shape memory effect and super elasticity effect of the material. By implementing this model as a user subroutine in the FE code Abaqus/Standard, it becomes possible to account for variations in material properties in complex components made of shape memory alloys. To demonstrate the potential of the proposed model, a skid plate system design is presented. The system uses bistable actuators with shape memory alloy springs to trigger plate movement. The kinematics and dynamics of the system are simulated, and effective loads are generated by the shape memory alloy state change due to the real temperature distribution in the material, which depends on the springs' geometrical parameters. Finally, the performance of the actuator in switching between different configurations and maintaining stability in a specific configuration is assessed. The study highlights the promising potential of shape memory alloys in engineering applications and demonstrates the ability to use them in complex systems with accurate simulations.

Cryogenic superelasticity and elastocaloric effect in a nanostructured Ti-Ni-Co alloy

We report a nanostructured Ti49.2Ni44.8Co6 (at.%) alloy that exhibits a fully recoverable tensile superelasticity (∼ 6%) with high critical stress (> 500 MPa) spanning low temperatures from -150 to -50 ∘C. An adiabatic temperature change reaches 10.7 K during fast unloading at -50 ∘C. The low-temperature tensile superelastic stress and adiabatic temperature change outperform most shape memory alloys. Moreover, both properties exhibit negligible degradation during dozens of stress cycles. We attribute these favorable functionalities to the enhanced thermodynamic stability of parent phase and the remarkable strengthening effect on the matrix by partially recrystallized nanocrystalline structure with dispersed Ti3Ni4 nanoprecipitates.

Integrating near‐surface mounted SMA and externally bonded CFRP for concrete beams strengthened in flexure

AbstractThis study aims to develop a new hybrid strengthening approach for reinforced concrete beams by integrating near‐surface mounted shape memory alloys (SMAs) and externally bonded carbon fiber reinforced polymers (CFRPs). Due to the superelasticity and shape memory effect of SMAs, the proposed strengthening can enhance the flexural strength of concrete beams without compromising ductility. The recovery behavior of deformed SMA wires was studied to determine the optimal prestrain level that can achieve the highest recovery stress. Afterward, the flexural performance of concrete beams strengthened with SMA, CFRP and both was investigated by performing three‐point tests. The results show that integrating SMA and CFRP has more influence on increasing the ultimate moment than the cracking moment and leads to a more significant improvement in the ultimate moment than individually utilizing SMA and CFRP. Besides, the effect of the integrated approach on enhancing the ductility is more notable than increasing the ultimate moment. The ultimate moment was analytically calculated, and the calculations show reasonable agreement with experimental results. The effects of the SMA and CFRP amount on the ultimate moment were also clarified through a parametric study.

Superelasticity and elastocaloric effect in a textured Ti-Nb-Zr-Ta alloy with narrow stress hysteresis

Recently, elastocaloric cooling has been authoritatively regarded as the most promising alternative for replacing conventional vapor compression technology, yet obstacles like structural/functional fatigue and high processing cost still exist, which boost the investigation of new elastocaloric materials. In this paper, we investigated the superelasticity (SE) as well as the elastocaloric effect (eCE) in a textured Ti-22 Nb-4Zr-2Ta alloy prepared by cold rolling of 97% in thickness and subsequent annealing at 973 K for 30 min. The strong texture is in favor of harmonizing the superelastic critical stress and enhancing transformation homogeneity. As a result, superelasticity with narrow stress hysteresis of ∼47 MPa at ambient temperature and outstanding homogeneous eCE has been confirmed elaborately through observing strain together with temperature distribution during a superelastic cycle. The standard deviations (Sdev) of the strain distribution during superelastic deformation was in the range of 0.17%− 0.37% accompanying with temperature change (ΔTadi) of ∼4.4 K and ∼3.9 K during loading and unloading processes, respectively. Moreover, the narrow superelastic hysteresis and homogenous transformation behavior allowed for a coefficient of performance (COP) value of 13.2 and little degradation after 240 elastocaloric cycles. As eCE homogeneity and SE hysteresis correlate closely with functional fatigue behavior, the present Ti-22 Nb-4Zr-2Ta alloy may act as potential working materials for stable solid-state refrigeration.