Size dependence of martensite transformation temperature in nanostructured Ni–Mn–Sn ferromagnetic shape memory alloy thin films

Vishnoi, Ritu; Kaur, Davinder

doi:10.1016/j.surfcoat.2010.04.053

Cited by 44 publications

(24 citation statements)

References 40 publications

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“…1. XRD analysis reveals the formation of martensitic phase in pristine film, and the planes corresponding to martensitic structure are marked by their Miller indices [21][22][23][24]. The lattice constants a, b, and c are estimated to be about 0.4, 0.5 and 2.9 nm, which agrees with the previously reported values of lattice constants for bulk [25].…”

Section: Structural Propertiessupporting

confidence: 87%

Phase transformation in Ni–Mn–Sn ferromagnetic shape memory alloy thin films induced by dense ionization

et al. 2012

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The effects of 200 MeV Au ions irradiation on the structural and magnetic properties of Ni-Mn-Sn ferromagnetic shape memory alloy (FSMA) thin films have been systematically investigated. In order to understand the role of initial microstructure and phase of the film with respect to high energy irradiation, the two types of Ni-Mn-Sn FSMA films having different phases at room temperature were irradiated, one in martensite phase (Ni 58.9 Mn 28.0 Sn 13.1 ) and other in austenite phase (Ni 50 Mn 35.6 Sn 14.4 ). Transmission electron microscope (TEM) and scanning electron microscope (SEM) images along with the diffraction patterns of X-rays and electrons confirm that martensite phase transforms to austenite phase at a fluence of 6 × 10 12 ions/cm 2 and a complete amorphization occurs at a fluence of 3 × 10 13 ions/cm 2 , whereas ion irradiation has a minimal effect on the austenitic structure (Ni 50 Mn 35.6 Sn 14.4 ). Thermomagnetic measurements also support the above mentioned behaviour of Ni-Mn-Sn FSMA films with increasing fluence of 200 MeV Au ions. The results are explained on the basis of thermal spike model considering the core and halo regions of ion tracks in FSMA materials.

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Section: Structural Propertiessupporting

confidence: 87%

Phase transformation in Ni–Mn–Sn ferromagnetic shape memory alloy thin films induced by dense ionization

et al. 2012

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“…A size effect was also observed in deposited films of Ni-Mn-Sn alloys in which the ferromagnetic shape memory effect takes place in the massive state [52]. In these alloys, the influence of grain size on proceeding of MT found out also.…”

Section: Nucleation and Martensitic Transformation In Small Dimensionmentioning

confidence: 71%

Nucleation and Martensitic Transformation in Subjects of Small Dimensions

Lobodyuk

2014

Usp. Fiz. Met.

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The existing models and schemes of the martensitic phase nucleation are considered in the review. Theoretical and experimental works devoted to the nucleation of the martensitic crystals in different metals are discussed and analysed. The parameters and processes of the martensitic transformation in such subjects of small dimensions as particles, porous materials, thin films, nanoparticles, and nanomaterials are also considered and discussed.В огляді розглядаються наявні моделі та схеми зародження мартенсит-них фаз, обговорюються теоретичні й експериментальні роботи, прис-вячені зародженню кристалів мартенситу в різних металах. Розгляда-ються й обговорюються параметри та процеси мартенситного перетво-рення у таких об'єктах малих розмірів як частинки, порошкові матері-яли, тонкі плівки, наночастинки та наноматеріяли.В обзоре рассматриваются существующие модели и схемы зарождения мартенситных фаз, обсуждаются теоретические и экспериментальные работы, посвящённые зарождению кристаллов мартенсита в различных металлах. Рассматриваются и обсуждаются параметры и процессы мар-тенситного превращения в таких объектах малых размеров как частицы, порошковые материалы, тонкие плёнки, наночастицы и наноматериалы.

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“…Decreasing the ratio of grain size to specimen size leads to a stricter compatibility requirement and thus inhibits the martensitic phase transformation. In fact, the increase in the critical martensitic transformation stress O-Ms and the decrease in the martensite start temperature Ms for decreasing grain size-to-specimen size ratio were reported in [109, 122,71,120]. In addition, Chen and Schuh proposed another intrinsic size-dependent effect.…”

Section: Experimentally Observed Size-dependent Mechanical Responses mentioning

confidence: 90%

Computational modeling of size-dependent superelasticity of shape memory alloys

Qiao

Radovitzky

2016

Journal of the Mechanics and Physics of Solids

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The superelastic effect in shape memory alloys (SMAs) is attributed to the stressinduced reversible austenitic-martensitic phase transformations. It is characterized by the development of significant strains which are fully recoverable upon unloading, and also characterized by the stress-hysteresis in the loading and unloading cycle which corresponds to the energy dissipated during phase transformations. Recently, experiments have revealed size-dependent effects in the superelastic responses of SMAs at micro-and nanoscales. For instance, the CuAlNi microwires and submicron pillars show a substantially higher capacity for the energy dissipation than that of bulk samples, which offers a significant promise for the applications in protective materials.In this thesis, a continuum model is developed in order to improve our understanding of size effects in SMAs at small scales. The modeling approach combines classic superelastic models, which use the volume fraction as an internal variable to represent the martensitic phase transformation, with strain gradient plasticity theories. Size effects are incorporated through two internal length scales, an energetic length scale and a dissipative length scale, which correspond to the martensitic volume fraction gradient and its time rate of change, respectively. Introducing the gradient of the martensitic volume fraction leads to coupled macro-and microforce balance equations, where the displacements and the martensitic volume fraction are both independent fields. A variational formulation for the temporally-discretized coupled macro-and microforce balance equations is proposed, as well as a computational framework based on this formulation. A robust and scalable parallel algorithm is implemented within this computational framework, which enables the large-scale three-dimensional study of size effects in SMAs with unprecedented resolution. This modeling and computational framework furnishes, in effect, a versatile tool to analyze a broad range of problems involving size effects in superelasticity with the potential to guide microstructure design and optimization. In particular, the model captures the increase of the stress hysteresis and strain hardening in bulk polycrystalline SMAs for decreasing grain size, as well as the increase of the residual strain for decreasing pillar size in NiTi pillars. The model confirms that constraints like grain boundaries 3 and the surface Ti oxide layer are responsible for the size-dependent superelasticity in SMAs.

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Size dependence of martensite transformation temperature in nanostructured Ni–Mn–Sn ferromagnetic shape memory alloy thin films

Cited by 44 publications

References 40 publications

Phase transformation in Ni–Mn–Sn ferromagnetic shape memory alloy thin films induced by dense ionization

Phase transformation in Ni–Mn–Sn ferromagnetic shape memory alloy thin films induced by dense ionization

Nucleation and Martensitic Transformation in Subjects of Small Dimensions

Computational modeling of size-dependent superelasticity of shape memory alloys

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