Martensitic transformation and mechanical properties of Ni49+xMn36–xIn15 (x=0, 0.5, 1.0, 1.5 and 2.0) alloys

Zhou, Le; Mehta, Abhishek; Giri, Anit K.; Cho, Kyu; Sohn, Yong Ho

doi:10.1016/j.msea.2015.08.034

Cited by 14 publications

(4 citation statements)

References 41 publications

(27 reference statements)

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“…The E r varies from approximately 85 GPa to 135 GPa depending on the composition. The value is close to that reported for the bulk NiMnGa alloys [11]. A relative minimum is observed for all three nanoindentation profiles, and the minimum value occurs near the interphase boundary between the austenite and martensite.…”

Section: Defect and Diffusion Forum Vol 371supporting

confidence: 88%

A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys

Zhou

Giri

Cho

et al. 2017

DDF

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The ferromagnetic shape memory and magnetocaloric properties of NiMnGa alloys are closely related to the martensitic transformation from high temperature austenitic phase to low temperature martensitic phase. The transformation temperature and the resulting microstructure and crystallography of the martensites can be very complex, but are crucial to the optimization of the material performance. A combinatorial study with a series of solid-to-solid diffusion couples and various characterization techniques, including scanning electron microscopy, focused ion beam, transmission electron microscopy, electron probe microanalysis, and nanoindentation, was carried out to investigate the microstructural and crystallographic development, and mechanical properties in NiMnGa alloys. Both austenitic and martensitic phases were found at room temperature in each diffusion couple with a clear interphase boundary. Crystallographic variations in martensitic phase, including non-modulated (NM) martensite and modulated (5M or 7M) martensite, were found in the diffusion couples. All martensitic microstructure consists of variants with different orientations and the twinning relationship. A decrease of reduced elastic modulus (Er) was observed with Ni substituting for Ga in the austenitic phase. However, an opposite trend of an increase in Er was found in the martensitic phase. The softening of the elastic constants near the vicinity of martensitic transformation contributed to a sharp decrease in Er near the interphase boundary. The measured Er had a larger scatter for the martensitic phase than that for the austenitic phase.

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Section: Defect and Diffusion Forum Vol 371supporting

confidence: 88%

A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys

Zhou

Giri

Cho

et al. 2017

DDF

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“…In addition, the H varied approximately from 3.5 GPa to 5.5 GPa for both the martensitic and austenitic phase. Results obtained from this combinatorial approach is close to that reported in bulk NiMnGa alloys [40].…”

Section: Diffusion and Thermal Transport In Bulk And Nano-materialssupporting

confidence: 84%

Diffusion and its Application in NiMnGa Alloys

Zhou

Sohn

2018

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Heusler NiMnGa alloys are often categorized as ferromagnetic shape memory alloys or magnetocaloric materials, which are important for both practical applications and fundamental research. The NiMnGa alloys undergo a series of diffusion and diffusionless transformation from high temperature to low temperature. Among these transformation, martensitic transformation from austenitic phase to martensitic phase is critical in determining the properties of the alloys. Although martensitic transformation is considered diffusionless, diffusion also has important applications in the research of NiMnGa alloysDiffusion couples along with equilibrium alloys have been used to determine the ternary phase diagrams in NiMnGa alloys. Phase diagrams are important in selecting NiMnGa alloys, in particular two-phase NiMnGa alloys for practical applications. Furthermore, the diffusion couples effectively assist in the determination of compositions that exhibit martensitic transformation temperature near room temperature. Diffusion coefficients have been assessed for NiMnGa alloys. Tracer diffusivity of Ni, Mn and Ga was reported in a wide temperature range and followed Arrhenius behavior. Two different activation energies were obtained, corresponding to B2 and L21 crystal structure, respectively. Interdiffusion coefficients for NiMnGa alloys with B2 crystal structure are measured, which showed that Ni diffuses the fastest, followed by Mn then Ga. The diffusion coefficients provide useful information for fabricating NiMnGa alloys through diffusional process.A combinatorial approach involving diffusion couples and advance characterization has been developed to investigate the mechanical properties, microstructure and crystallography of NiMnGa alloys rapidly and systematically over a large compositional range. The composition-dependent modulus and hardness for NiMnGa alloys was extracted from the diffusion couples with the help of nanoindentation. Martensitic phases with non-modulated and various modulated crystal structures, and austenitic phase were identified in the interdiffusion zones by transmission electron microscopy. The results demonstrate the capability of using diffusion couples to speed up the discovery of new NiMnGa alloys or other similar alloys showing martensitic transformation.

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“…The chosen alloys exhibit low-temperature martensite transforming to austenite at higher temperatures from both microstructural and magnetic observations. Further details of their synthesis, structural characterization, and magnetocaloric properties can be found in References [26,27]. Their temperature dependence of magnetization is shown in Figure 1a for which various magnetic phase transitions upon heating can be observed: a martensitic (martensite to austenite) transition (FOPT) followed by a Curie transition of the austenitic phase at higher temperatures (SOPT).…”

Section: Resultsmentioning

confidence: 99%

Influence of Thermal and Magnetic History on Direct ΔTad Measurements of Ni49+xMn36−xIn15 Heusler Alloys

Moreno-Ramírez

Delgado-Matarín

Law

et al. 2019

Metals

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In the present work, using Heusler Ni49+xMn36-xIn15 (with x = 0 and 0.5) alloys, it is shown that the choice of the appropriate measurement protocol (erasing the prior state of the sample in between experiments) in ∆Tad first shot characterization is crucial for obtaining reliable results. Unlike indirect measurements, for which incorrect protocols produce overestimates of the characteristics of the material, erroneous direct measurements underestimate ∆Tad in the region close to its first order phase transition. The error in ∆Tad is found to be dependent on the temperature step used, being up to ~40% underestimation, including a slight shift in its peak temperature.

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Martensitic transformation and mechanical properties of Ni49+xMn36–xIn15 (x=0, 0.5, 1.0, 1.5 and 2.0) alloys

Cited by 14 publications

References 41 publications

A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys

A Combinatorial Study for Interdiffusion, Crystallography and Mechanical Behavior of Ni-Mn-Ga Alloys

Diffusion and its Application in NiMnGa Alloys

Influence of Thermal and Magnetic History on Direct ΔTad Measurements of Ni49+xMn36−xIn15 Heusler Alloys

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