Martensitic Phase Transition Research Articles

Tailoring β-Ti based shape memory alloy with the exceptional mechanical and functional properties towards biomedical bone implants application

In the present study, the interstitial hydrogen (H) atoms were introduced as β-stabilizing element to tailor the microstructure, martensitic phase transition, and functional properties of Ti-V-Al shape memory alloys for biomedical applications. The results revealed that the addition of interstitial H atoms into Ti-V-Al shape memory alloys induced the transition from a single αˊˊ martensite to the coexistence of β parent phase and α phase, regardless of H content. Moreover, the amount of α phase firstly increases and then decreases in the present Ti-V-Al based shape memory alloy with H content increasing. Besides, H addition resulted in larger lattice distortion, further causing the formation of nano-domains in Ti-V-Al based alloys. Besides, no endothermic and exothermic peaks were detected due to the confinement of α-phase, and the emergence of nano-domains. With increasing H atoms content, the mechanical properties such as fracture strength, hardness, recoverable strain for Ti-V-Al based shape memory alloys initially increased and then decreased. (Ti-13V-3Al)99.2H0.8 shape memory alloys exhibited the highest fracture strength of 862MPa, superior hardness of 307HV, and the fully recoverable strain under 6% pre-strain as well as the moderate elastic modulus, which was mainly attributed to the solution strengthening of interstitial H atoms and the precipitation strengthening of α phase. The best corrosion resistance of Ti-V-Al based shape memory alloys was observed with the 2.0at. % H, which was due to the formation of TiO2, Ti2O3 oxide films. Moreover, the best wear resistance with the lower wear rate of 0.9347×10-6 mm3/N mm was obtained in (Ti-13V-3Al)99.2H0.8 shape memory alloy, due to the integrated effects of higher microhardness, reinforcing effect of α phase and lubrication effect of the hydrogenated film.

Demonstration of a container-less method for investigating high-temperature alloy properties using ED-XRD.

As new alloys are being developed for additive manufacturing (AM) applications, questions related to the temperature-dependent structural and compositional stability of these alloys remain. In this work, the benefits and limitations of a unique method for testing this stability are presented. This system employs the use of polychromatic synchrotron light to perform energy-dispersive x-ray diffraction (ED-XRD) on an electrostatically levitated sample at high temperatures. In comparison with a traditional angular-dispersive setup, the container-less electrostatic levitation method has unique advantages, including quicker acquisition times, simultaneous compositional information through fluorescence emissions, a reduction in background noise, and, importantly, concurrent/subsequent measurement of thermophysical properties. This combined method is ideal for phase transition studies by holding the levitated sample at a stable position and temperature through controlled heating and temperature management. To illustrate these capabilities, we show ED-XRD data of the well-known martensitic phase transition (hcp to bcc) in Ti-6Al-4V. In addition, results from the novel alloy Ni51Cu44Cr5 are presented. This alloy is shown to maintain an fcc structure upon heating. However, the concentration of Cu is reduced at high temperatures, resulting in a decrease in the lattice constant. As concurrent thermophysical properties are probed, these preliminary structure and composition experiments demonstrate the capabilities of this technique to determine the composition-processing-structure-properties of metal alloys for AM.

Electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds: the case of Pd2MnTi

Abstract In this study, taking Pd2MnTi as a representative example, the electronic structure evolution during martensitic phase transition in all-d-metal Heusler compounds was systematically studied and revealed theoretically. The calculation and theoretical analysis suggest that Pd2MnTi is not stable in cubic structure and prones to transform to low-symmetric tetragonal structure. By tetragonal deformation, the shrinkage of lattice parameters and the decrease of symmetry promote the electron accumulation between Pd and its first nearest neighboring Ti atom, resulting in the increased covalent hybridization. The occurrence of pesudogap in density of states (DOSs) of tetragonal Pd2MnTi near the Fermi level also verifies the enhancement of covalent bond. Comparatively, the stronger interatomic bond in tetragonal Pd2MnTi, i.e., covalent bond here, would strengthen interatomic coupling and consequently lower the energy of the material. By the martensitic phase transition, more stable state in energy was achieved. Thus, based on the analysis of electronic structure evolution, the nature of martensitic phase transition is a process wherein symmetry breaking weakens the original weak chemical bonds in high-symmetric parent phase and induces the strong chemical bond to lower the energy of the materials and achieve a more stable state. This study could help to deepen the understanding of martensitic phase transition and the exploration of novel materials for potential technical applications.

Effect of Thermal Load Caused by Tread Braking on Crack Propagation in Railway Wheels on Long Downhill Ramps

To investigate the propagation behavior of thermal cracks on the wheel tread under the conditions of long downhill ramps, a three-dimensional finite element model of a 1/16 wheel, including an initial thermal crack, was developed using the finite element software ANSYS 17.0. The loading scenarios considered include mechanical wheel–rail loads, both with and without the superposition of thermal wheel–brake shoe friction loads. The virtual crack closure method (VCCM) is employed to analyze the variations in stress intensity factors (SIFs) for Modes I, II, and III (KI, KII, and KIII) at the 0°, mid, and 90° positions along the crack tip. The simulation results show that temperature is a critical factor for the propagation of thermal cracks. Among the SIFs, KII (Mode II) is larger than KI (Mode I) and KIII (Mode III). Specifically, the thermal load on the wheel tread during braking contributes up to 23.83% to KII when the wheel tread reaches the martensitic phase transition temperature due to brake failure. These results are consistent with the observed radial propagation of thermal cracks in wheel treads under operational conditions.

Phase transition in the shape memory alloy NiTi described by the SCAN meta-GGA functional.

Climbing the ladder of density functional approximations has long been proposed to systematically improve the accuracy of first-principles calculations employing the density functional theory (DFT); however, up until now, the Perdew-Burke-Ernzerhof (PBE) functional at the second rung of the ladder, has dominated. Here, we present a study of the martensitic phase transition in NiTi based on abinitio molecular dynamics simulations and thermodynamic integration using the third-rung approximation of the strongly constrained and appropriately normalized (SCAN) meta-generalized gradient approximation (GGA). Although the predicted equilibrium lattice constants and formation enthalpy agree well with experimental data, the martensitic transition temperature (MTT) is overestimated by 94% (or 324K too high), compared with only 22% (77K) overestimation by PBE. The latent heat (q) is severely overestimated by SCAN as well. This deteriorated performance originates from the enlarged energy difference (ΔE) between the austenite and martensite phases, compared with the PBE result. Furthermore, a large variation (over 50meV/atom) in ΔE using different meta-GGAs indicates large variations in computed MTTs (∼400-500 K) and q, i.e., the predicted thermodynamic properties depend sensitively on the choice of meta-GGA. This would pose a serious problem when upgrading DFT calculations to the third rung. One possible solution is to add NiTi as a normsystem so that the revised SCAN meta-GGA could reproduce the PBE results of the relevant energy difference.

Giant Thermosalient Effect in a Molecular Single Crystal: Dynamic Transformations and Mechanistic Insights.

The exploration of mechanical motion in molecular crystals under external stimuli is of great interest because of its potential applications in diverse fields, such as electronics, actuation, or sensing. Understanding the underlying processes, including phase transitions and structural changes, is crucial for exploiting the dynamic nature of these crystals. Here, we present a novel organic compound, PT-BTD, consisting of five interconnected aromatic units and two peripheral alkyl chains, which forms crystals that undergo a drastic anisotropic expansion (33% in the length of one of its dimensions) upon thermal stimulation, resulting in a pronounced deformation of their crystal shape. Remarkably, the transformation occurs while maintaining the single-crystal nature, which has allowed us to follow the crystal-to-crystal transformation by single-crystal analysis of the initial and expanded polymorphs, providing valuable insights into the underlying mechanisms of this unique thermosalient behavior. At the molecular level, this transformation is associated with subtle, coordinated conformational changes, including slight rotations of the five interconnected aromatic units in its structure and increased dynamism in one of its peripheral alkyl chains as the temperature rises, leading to the displacement of the molecules. In situ polarized optical microscopy reveals that this transformation occurs as a rapidly advancing front, indicative of a martensitic phase transition. The results of this study highlight the crucial role of a soft and flexible structural configuration combined with a highly compact but loosely bound supramolecular structure in the design of thermoelastic materials.

Investigation of phase stability and martensitic transformation of all-d-metal Heusler alloys Fe2VIr and Fe2TaIr in high pressure: A first-principles study

First-principles calculations are used to investigate the phase stability and martensitic transformation of two new all-d-metal Heusler alloys Fe2VIr and Fe2TaIr at 0–50 GPa. The difference in phase stability between Fe2VIr and Fe2TaIr is due to the effect of d-d orbital hybridisation between different atoms and the appearance of triply degenerate in the pressure-induced phonon optical modes. The softening behaviour of the transverse phonon mode along the high symmetry point X is responsible for the martensitic transformation of Fe2TaIr. We also observed the softening of the shear elastic constant C′ = (C11-C12)/2. Strong Fe-Fe magnetic coupling, softening of transverse acoustic phonon modes and anomalous softening of C′ awaken the martensitic transformation. Low-frequency phonon hybridisation of the heavy elements Ta and Ir is the driving force behind the softening. A surprising phenomenon is found during tetragonal deformation of the structure of Fe2TaIr at 45 GPa, whereby the structure break through the energy barrier of the leap and produced a tetragonal martensitic phase with a much lower energy. It may imply that pressure-induced Fe2TaIr produced a premartensitic phase. This work presents a detailed analysis of the anomalous softening behaviour of Fe2TaIr and the mechanism of the pressure-induced martensitic transformation. A new idea is proposed for an in-depth study of the martensitic phase transition precursor reaction.

Effects of preexisting dislocations on phase transition and deformation of NiTi shape memory alloy: An in situ multi-scale study

Phase transition and deformation in cold-rolled and heat-treated Ni50.6Ti49.4 alloys are explored by in situ multi-scale measurements with simultaneous X-ray diffraction and optical digital image correlation. Macroscale stress−strain curves, mesoscale strain fields and microscale X-ray diffraction peaks are obtained. Electron backscatter diffraction and transmission electron microscopy are also conducted on samples before and after tension as complements. For cold-rolled samples, since martensite nucleation is strongly associated with the widely distributed preexisting dislocations, homogeneous martensite phase transition takes place, in contrast with the localized mode in heat-treated samples. For localized phase transition, the intense growth of martensite results in clear Lüders bands. The beginning and the end of phase transition plateau on the stress−strain curve are associated with the initiation and complete propagation of Lüders bands. For the homogeneous phase transition, broad growth of martensite leads obscure Lüders bands and uniform strain fields, without any phase transition plateau. Given the initial {110}〈110〉 and {111}〈110〉 sheet textures in the heat-treated samples, different martensite variants with different preferred orientations are activated with respect to the loading directions.

Hysteresis gap-shrinking and structural effects of minor Al and Ti modifications on binary CuAl-based high-temperature shape memory alloys

Cu-based shape memory alloys (SMAs), except for exhibiting shape recovery, superelasticity, and high damping, are desirable because these smart materials have higher electrical and thermal conductivity and much lower prices than NiTi SMAs. However, they also have some downsides in mechanical strength and brittleness (mostly stemming from their coarse grain structure) and thermal instability. Therefore, adding some grain refining elements to these SMAs to improve their shape memory effect (SME), and thermal, structural, and mechanical properties is a widespread and simple way that significantly affects their martensitic phase transitions, structure, and mechanical properties. One of these grain-refining elements is titanium. Its thermal conductivity is lower than those of Cu and Al elements and has a low solubility in Cu-matrix. Besides the effects of small Al variations, the use of minor amounts of titanium in binary CuAl-base alloys can show impressive effects on all characteristics of these shape memory alloys, such as shape memory effect properties, martensitic transformation kinetics parameters, and microstructural features. In this research work, CuAlTi ternary high-temperature shape memory alloys (HTSMAs) with new compositions were produced by the arc melting method without a complicating use of Mn or Ni components in usual ternary CuAlMn and CuAlNi shape memory alloys. Thermal analyses of the prepared samples of the alloys were investigated by using differential scanning calorimetry (DSC) and differential thermal analysis (DTA) measurements. In contrast, x-ray diffraction (XRD) test results and optical micrographs were used for analyzing the structure of the alloy samples. The effect of different amounts of low soluble and grain refining Ti element on the binary CuAl alloy system was investigated.

Investigation of the effect of martensitic phase transition temperature and Curie temperature difference on magnetic and magnetocaloric properties under low magnetic field on Si-doped Ni-Mn-In Heusler alloys

This study examines the impact of substituting Si for Mn on the structural, magnetic, and magnetocaloric properties of Ni43Mn46−x Si x In11 (x = 0.3 and 0.6) alloys. To this end, a range of analytical techniques are employed, including scanning electron microscopy (SEM), room temperature x-ray powder diffraction (XRD), and magnetization measurements. Above the martensitic transition temperature, the Ni43Mn46−x Si x In11 alloys exhibit cubic L2 1 (space group FM-3M). Below this temperature they adopt a tetragonal L1 0 (space group I4/mmm). The martensitic transition temperature decreased when Si is substituted for Mn. The magnetic field-induced entropy change is calculated from magnetic field-dependent magnetization measurements using Maxwell’s equations. The maximum magnetic field-induced entropy changes for Ni43.16Mn45.56Si0.29In11 and Ni43.51Mn44.82Si0.59In11 alloys are calculated 8.20 J kg−1K−1 and 3.15 J kg−1 K−1, respectively, in the vicinity of the magnetostructural phase transition for a magnetic field change of 18 kOe. It is demonstrated that the temperature differential between the high-temperature austenite phase's Curie point (T C ) and the mean martensitic transformation temperature (T M ), namely (T M -T C ), influences the martensitic transition temperatures and, consequently, on the magnetic field-induced entropy change (ΔS M ).

A first-principles study of the phase transitions in ultrahigh temperature shape memory alloy RuNb

Ultrahigh temperature shape memory alloys (UHT-SMAs) have transition temperatures above 600 °C. They are needed for sensing and actuating devices in aerospace applications. However, very few such UHT-SMAs have been found. Among them are Ru-based alloys such as RuNb and RuTa, whose martensite structures and phase transitions are totally different from those of NiTi-based SMAs and were poorly understood. In this work, we carried out a systematical study of RuNb using first-principles total energy calculations and molecular dynamics (MD) simulations. We revealed the transition paths and mechanisms in cubic → tetragonal → monoclinic transitions. We determined the transition sequence and martensitic transition temperatures (MTTs) by evaluating the Gibbs free energies using thermodynamic integration. The calculated MTTs are in very good agreement with the experimental data. We also found that the monoclinic phase at the second transition has the P21/m symmetry instead of experimentally identified P2/m. The insights gained by this study and the verified ab initio methods for accurate MTT calculations can be applied to fast screen and quantitatively design novel UHT-SMAs having similar properties with desirable MTTs and much reduced cost.

Elucidation of annealing effects on austenite–martensite and magnetic phase transitions in Mn2Ni1.6Sn0.4 ribbons synthesized from bulk alloys prepared by RF induction melting

We investigate the consequences of annealing on the structure, microstructure, magnetic, and electrical transport of Mn2Ni1.6Sn0.4 ribbons. The 40–60 μm thick ribbons were formed by melt spinning of the bulk ingot synthesized by RF induction melting. Ribbons were annealed at 600 °C for 12 hrs and the other at 800 °C for 2 hrs in vacuum. All ribbons crystallize into a cubic symmetry (space group F4¯3m). The orthorhombic phase appears as the secondary one. In ribbons annealed at 600 °C, the crystallite size decreases from ∼ 47 nm to ∼ 29 nm, and annealing at 800 °C doubles the crystallite size to ∼ 96 nm. The least amount of microstrains (17x10−4) in the as-synthesized ribbon is consistent with the occurrence of the superlattice peaks (111) and (200). Lower intensities of the superlattice peaks in 600 °C and 800 °C ribbons are consistent with higher microstrains (25x10−4 and 24x10−4). Hence, a higher degree of Ni-Mn ordering improves magnetic properties in annealed samples. The as-synthesized ribbon has an austenite-phase Curie temperature of TCA∼303K, which enhances to TCA∼320K and TCA∼310K after annealing at 600 °C and 800 °C. The ribbon annealed at 600 °C has the highest saturation moment. All the ribbons show the exchange-bias (EB) effect, and the most pronounced effect is seen in the 800 °C annealed ribbon. Microstructure uniformization and relative strengths of the Ni-Mn and Mn-Mn interactions improve the magnetics. Near TC, MT=M0TC-Tβ is satisfied (β = 0.31, 0.36, and 0.37, for as-synthesized, 600 °C and 800 °C annealed ribbons). The low-temperature spontaneous magnetization obeys the Bloch law MT=M01-AT32, with a deviation in 600 °C annealed ribbon due to spin freezing. The ρ-T has been fitted in the different temperature ranges using the various combinations in ρT=ρ0+AphT+BsdTα. At T < 85 K, the resistivity of the as-synthesized ribbon follows ρT=ρ0+BsdTα, with α≈1.47, while for the 600 °C annealed ribbon, α≈1.49. The exponent α∼1.5 supports the existence of the spin glass state in the lower temperature region of as-synthesized and 600 °C annealed ribbons. In the high-temperature range, the linear ρ-T behavior is described by ρT=ρ0+AphT and consistent with the electron–phonon scattering.

Interplay between the reversibility of the inverse magnetocaloric effect and kinetic arrest in Ni-Co-Mn-Sn Heusler alloys

The nature of martensitic phase transitions and its modification as a function of composition and application of magnetic field have been studied in detail for Ni40Co10Mn40Sn10-xGax (x=0, 0.3, 0.4 and 0.5). The phase transition temperature (TM) increases with increasing x. The kinetic arrest (KA) of the austenitic phase has been observed for x=0 and 0.3, which disappeared for x>0.3. The KA results in a decrease in the change of magnetization (ΔM) across TM. However, the isothermal entropy change ΔS varies almost linearly with [dTM/d(μ0H)]−1 (field-induced shift in TM) irrespective of the composition variation and thermal cycling. This behavior indicates that the variation of dTM/d(μ0H) is the dominant factor determining the magnitude of the ΔS rather than ΔM. Consequently, the effect of KA on ∆M has a negligible influence on ΔS in the studied Heusler alloys. The reduced field-sensitivity in TM associated with the temperature-induced decrease of magnetization in the ferromagnetic austenitic phase leads to a decrease of the thermal hysteresis and an increase of ΔS. As a result, a large reversible (|ΔSrev|=21 J/kg K for Δμ0H=5 T) has been observed for x=0.5, which exceeds previously reported values for Sn-based Heusler alloys.

Revealing contrary contributions of the magnetic and lattice entropy to the inverse magnetocaloric effect in magnetic shape memory alloy

In this work, we studied the nature and dilemma of the inverse magnetocaloric effect using Ni50Mn36In14 magnetic shape memory alloy. In this context, the inverse magnetocaloric effects of Ni50Mn36In14 magnetic shape memory alloy polycrystalline samples were investigated as a function of annealing heat treatments by the thermo-magnetometry method. Two forms of Ni49TiMn36In14 magnetic shape memory alloy were studied: one that predominantly undergoes a magnetic phase transition and the other that exhibits both a magnetic and martensitic phase transition. The magnetic behaviors and magnetocaloric properties of these alloys were analyzed to investigate the competition between magnetic and lattice contributions to the total entropy change. Finally, the mutually contradictory role of magnetic and lattice contributions was demonstrated.

Antiferroelectric Ceramics for Energy-Efficient Capacitors by Theory-Guided Discovery.

Antiferroelectric ceramics, via the electric-field-induced antiferroelectric (AFE)-ferroelectric (FE) phase transitions, show great promise for high-energy-density capacitors. Yet, currently, only 70-80% energy release is found during a charge-discharge cycle. Here, for PbZrO3-based oxides, geometric nonlinear theory of martensitic phase transitions is applied (first used to guide supercompatible shape-memory alloys) to predict the reversibility of the AFE-FE transition by using density-functional theory to assess AFE/FE interfacial lattice-mismatch strain that assures ultralow electric hysteresis and extended fatigue lifetime. A good correlation of mismatch strain with electric hysteresis, hence, with energy efficiency of AFE capacitors is observed. Guided by theory, high-throughput material search is conducted and AFE compositions with a near-perfect charge-discharge energy efficiency (98.2%), i.e., near-zero hysteresis are discovered. And the fatigue life of the capacitor reaches 79.5 million charge-discharge cycles, a factor of 80 enhancement over AFE ceramics with large electric hysteresis.

The varying nature of the martensitic phase transition and associated entropy changes in a Co and Cr doped pseudo-ternary Heusler alloy system

We have investigated the magnetostructural phase transitions and the associated entropy changes in a system of three Heusler alloys, namely: Ni2Mn0.55Cr0.45Ga, Ni2Mn0.55Co0.10Cr0.35Ga, and Ni2.15Mn0.75Cr0.1Ga. All three alloys exhibited first-order martensitic phase transition. An inter-martensitic phase transition raised the magnetic and structural phase transition temperatures, and partially decoupled the said transitions. Furthermore, field magnetization measurements demonstrated that a significant reduction in magnetic hysteresis is achieved in the Ni2Mn0.55Co0.10Cr0.35Ga compound, resulting in improved effective refrigerant capacity values. The largest magnetic entropy change of −23.5 J/kg K and refrigeration capacity of 97.7 J/kg were observed in Ni2.15Mn0.75Cr0.1Ga. This observation of mitigated deficiencies in materials experiencing a first-order phase transition is relevant towards their application in magnetic refrigeration.

Corrosion resistance of VC-reinforced Fe-based SMA coatings by laser cladding

The corrosion resistance of 42CrMo steel is insufficient to meet the demands in the marine environment, despite its widespread application in bearings and other fields. Herein, Fe-Mn-Si-Cr-Ni-χ(VC) shape memory alloy (SMA) composite coatings were successfully fabricated on the surface of 42CrMo steel using laser cladding technology. The results present that the coatings are mainly composed of γ austenite (fcc) phase and ε martensite (hcp) phase. Based on research findings, the incorporation of VC has been found to promote the γ → ε martensite phase transition in shape memory alloys. Simultaneously, electrochemical tests were conducted on 42CrMo substrate and SMA coating in 3.5 wt% NaCl solution. It was found that the coatings doped with an appropriate amount of VC could effectively enhance its corrosion resistance. When the doping amount of VC reaches 1.5 wt%, the charge transfer resistance (Rct) is significantly higher than that of the 42CrMo substrate and the pure SMA coating, as well as that of the coating doped with 2.0 wt% VC, reaching 21, 2.6, and 3.3 times of them, respectively. The charge transfer resistance Rct of LS1.5 is much higher than that of 42CrMo, LS0, and LS2.0, reaching 21, 2.6, and 3.3 times, respectively. Additionally, the maximal polarization resistance (Rp) of coatings achieves 4.39 times that of 42CrMo. This study points out that VC can efficiently boost the corrosion resistance of SMA composite coatings and may have uncovered a novel approach for improving the surface corrosion resistance of medium carbon steel.

An atomistic study of effects of temperature and Ni element on the phase transition and wear behavior of NiTi shape memory alloy

Phase transition and tribological behavior of NiTi alloys have drawn great attention. Molecular dynamics simulation was adopted to investigate the effects of temperature on the mechanical behavior and variant formation of NiTi, as well as its wear behavior. Thermally and stress-induced phase transition behavior of NiTi alloys were studied. It is found that residual austenite phase boundaries during martensitic phase transformation could inhibit martensitic phase transition, changing the phase transition temperatures, and the mechanical properties of NiTi. Wear behavior of single-crystal NiTi with a wide temperature domain and content was studied. The optimal wear resistance of NiTi was at 300 K during cooling. Appropriate improvement in Ni content is beneficial to the formation of martensite variants and enhancement of the wear resistance.

Simultaneous improvement of martensitic phase transition and ductility in Cu-doped and/or alloyed all-d-metal Ni2MnTa Heusler compounds.

Ductile all-d-metal Heusler compounds with tunable martensitic phase transition are desirable for solid-state refrigeration applications. The theoretical investigations on martensitic phase transition and ductile characteristics of novel all-d-metal Ni2MnTa were conducted in this study. By introducing Cu atoms into Ni2MnTa, the improvement of martensitic phase transition and ductility was simultaneously realized. It was found that the substitution of Cu with more valence electrons for Ni, Mn, and Ta atoms resulted in an increase in metallic bonding. Owing to the enhanced metallic bonding, elastic moduli were softened, which improved shear deformation ability and contributed to tailoring the austenite phase stability. Hopefully, the anticipated martensitic phase transition can be tailored to an optimal temperature range. Moreover, the increased metallicity accounted for the simultaneously enhanced ductility. The enhanced metallic characteristics also resulted in contracting lattice sizes of Cu-doped and/or alloyed Ni2MnTa compounds due to the volume effect. Metallic bonding may be described as the mechanism for simultaneously controlling the phase stability and enhancing ductile properties in Cu-doped and/or alloyed Ni2MnTa compounds. The calculated energy, electronic structure, and elastic parameters further verified the occurrence of martensitic phase transition in Cu-doped and/or alloyed Ni2MnTa compounds. Current results suggest that chemical bonding could be employed as a significant tuning factor in the exploration of multipurpose Heusler compounds.

Interface compatibility-induced quasi-volume-preserving martensitic phase transition in all-d-metal Co2NiT (T = Ti and V) Heusler compounds

The quasi-volume-preserving martensitic phase transition in all-d-metal Co2NiT (T = Ti and V) Heusler compounds results from the interface compatibility between high-symmetric cubic phases and low-symmetric tetragonal phases.