Role of point defects in stress-induced martensite transformations in NiTi shape memory alloys: A molecular dynamics study

Yang, Chao; Wharry, Janelle P.

doi:10.1103/physrevb.105.144108

Cited by 13 publications

(3 citation statements)

References 79 publications

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“…Deformation-induced martensitic transformation (DIMT) [1][2][3] plays an essential part in determining the mechanical properties of various kinds of crystalline materials such as highentropy alloys [4], shape memory alloys [5], and especially the austenitic stainless steels (AustSSs) widely used in the nuclear industry [6]. In irradiation environments, DIMT can be influenced by irradiation-induced microstructures, thus affecting the reliability and functionality of these materials [3,7,8]. For instance, it is found that DIMT in neutron-irradiated AustSSs is dramatically accelerated [9].…”

Section: Introductionmentioning

confidence: 99%

Model for deformation-induced martensitic transformation in irradiated materials

et al. 2023

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Deformation-induced martensitic transformation (DIMT) is commonly reported to be easily activated in irradiated materials, but the existing transformation kinetics models of DIMT hardly capture the irradiation effect. In this work, we develop a transformation kinetics model considering the effect of irradiation hardening, shear band evolution and the role of irradiation-induced voids. A crystal plasticity framework incorporating the newly developed transformation kinetics model is established. We show that the framework is capable of capturing the accelerated evolution of martensite volume fraction in both cases with and without irradiation-induced voids. Moreover, the framework successfully simulates two post-irradiation phenomena observed in experiments, i.e. the localized distribution of martensite fraction and the evolution of the dominant transformation pathway. The present work is one of the first attempts at the theoretical modelling of DIMT in irradiated materials, and has the potential to benefit the application of irradiation in tailoring the martensitic transformation behaviour.

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Section: Introductionmentioning

confidence: 99%

Model for deformation-induced martensitic transformation in irradiated materials

et al. 2023

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“…NiTi alloys have become a good candidate for MD simulations due to the development of several interatomic potentials able to capture both the stress-and temperature-induced martensitic transformations [24][25][26][27][28]. As a result, a number of MD studies on a wide range of topics in NiTi alloys have been performed in recent years [29][30][31][32][33][34][35][36][37][38]. The equiatomic NiTi alloy undergoes a martensitic transformation between a high temperature, cubic B2 phase and a low temperature, monoclinic B19 ′ phase [39].…”

Section: Introductionmentioning

confidence: 99%

Microstructural mechanisms of hysteresis and transformation width in NiTi alloy from molecular dynamics simulations

Plummer,

Mendelev,

Benafan

et al. 2023

J. Phys.: Condens. Matter

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Martensitic transformations in shape memory alloys are often accompanied by thermal hysteresis, and engineering this property is of prime scientific interest. The martensitic transformation can be characterized as thermoelastic, where the extent of the transformation is determined by a balance between thermodynamic driving force and stored elastic energy. Here we used molecular dynamics simulations of the NiTi alloy to explore hysteresis-inducing mechanisms and thermoelastic behavior by progressively increasing microstructural constraints from single crystals to bi-crystals to polycrystals. In defect-free single crystals, the austenite-martensite interface moves unimpeded with a high velocity. In bi-crystals, grain boundaries act as significant obstacles to the transformation and produce hysteresis by requiring additional nucleation events. In polycrystals, the transformation is further limited by the thermoelastic balance. The stored elastic energy can be converted to mechanisms of non-elastic strain accommodation, which also produce hysteresis. We further demonstrated that the thermoelastic behavior can be controlled by adjusting microstructural constraints.

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“…In materially uniform bodies, the heterogeneities, including the dislocations ( [7,8], Chapter 6 of [2]), accumulated plastic strains and shear bands [7,[10][11][12][13]15], crack tips [16], free surface [8,9], anti-phase boundaries [8], or any other regions within the materials with concentrated stresses [17,18], etc., are usually the preferred sites for nucleation of M in a single grain or polycrystalline samples of materials capable of undergoing martensitic transformations (MTs). The reduction in energies during MTs at other heterogeneous sites such as the matrix-precipitate interfaces [19], external surfaces of the samples [9,18,[20][21][22], and heterophase interfaces [23,24] also promotes the nucleation of M. On the other hand, point defects such as vacancies, interstitials, and ani-site defects may suppress the nucleation of M by significantly reducing the transformation temperatures [25,26].…”

Section: Introductionmentioning

confidence: 99%

Grain boundary-induced martensitic transformations: A phase-field study of nucleation, size-effect, triple junction-effect, microstructures, and compatibility at the nanoscale

Basak¹

2022

Preprint

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An original thermodynamically consistent large strains-based multiphase phase-field (PF) approach of Ginzburg-Landau type is developed for studying the grain boundary (GB)-induced martensitic transformations (MTs) in polycrystalline materials at the nanoscale considering the structural stresses within the interfaces. In this general PF approach, N independent order parameters are used for describing the austenite (A)↔martensite (M) transformations and N (> 1) martensitic variants, and another M independent order parameters are considered for describing M (> 1) grains in the polycrystalline samples.The change in the GB energy due to its structural rearrangement during MTs is considered using variable energy for the GB(s) as a function of the order parameter related to the A ↔ M transformation. A rich plot for the temperatures of transformations between the A, premartensite, and M in a bicrystal with a symmetric planar tilt GB are plotted for the varying austenitic GB width. The strong effects of the parameters, including the austenitic GB width, change in GB energy due to MTs, GB misorientation, applied strains, and sample size on heterogeneous nucleation of the phases and the subsequent complex martensitic microstructures evolution are explored in various bicrystals with symmetric or asymmetric planar or circular tilt GBs during the forward and reverse transformations. The triple junction (TJ) energy and the energy and width of the adjacent GBs are also shown to strongly influence the nucleation and microstructures using the tricrystals having three symmetric planar tilt GBs meeting at 120 • dihedral angles. The compatibility of the microstructures across the GBs is studied. The elastic and structural stresses across the GBs and TJ regions are plotted, which is essential for understanding the role of GBs and TJs in materials failure. The plausible reasons for the nonintuitive behaviour of the GBs on martensite nucleation observed in experiments and atomistic simulations are explained.

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Role of point defects in stress-induced martensite transformations in NiTi shape memory alloys: A molecular dynamics study

Cited by 13 publications

References 79 publications

Model for deformation-induced martensitic transformation in irradiated materials

Model for deformation-induced martensitic transformation in irradiated materials

Microstructural mechanisms of hysteresis and transformation width in NiTi alloy from molecular dynamics simulations

Grain boundary-induced martensitic transformations: A phase-field study of nucleation, size-effect, triple junction-effect, microstructures, and compatibility at the nanoscale

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