The mechanics of dynamic twinning in single crystal magnesium

Kannan, Vignesh; Hazeli, Kavan; Ramesh, K.T.

doi:10.1016/j.jmps.2018.03.010

Cited by 44 publications

(10 citation statements)

References 29 publications

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“…These results are in qualitative agreement with the stationary phase-field model under similar boundary conditions [137]. This needle-shaped lenticular twin, which has also been observed in [198], suggests that twin growth occurs by extension of a fast twin tip followed by a coordinated slower migration of the boundaries [199].…”

Section: Fracture-induced Twinning In Single Crystal Magnesiumsupporting

confidence: 88%

Thermodynamically-consistent derivation and computation of twinning and fracture in brittle materials by means of phase-field approaches in the finite element method

Amirian,

Jafarzadeh,

Abali

et al. 2022

Preprint

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A computational method is proposed for simulating and informing on controlling failure pattern development in anisotropic brittle solids experiencing extreme mechanical loading. Constitutive equations are derived by using thermodynamics in order to establish a fully coupled and transient fracture mechanics model. A phase-field approach is developed for modeling twinning, fracture, and fracture-induced twinning in single crystals at nanometer length-scale. At the nanoscale, this continuum mechanics based formulation is implemented in a monolithic computational scheme ensuring necessary accuracy for the following problems: (i) twin evolution in 2D single crystal magnesium and boron carbide under simple shear deformation; (ii) crack-induced twinning for single crystal magnesium under pure mode I and mode II loading; and (iii) study of fracture in homogeneous single crystal boron carbide under biaxial compressive loading. The results are verified by steady-state phase-field approach and validated by available experimental data in the literature. The success of this computational method relies on using two separate phase-field (order) parameters related to fracture and twinning. A finite element method-based code is developed within the Python-based open-source platform FEniCS. We make the code publicly available and the developed algorithm may be extended for the study of phase transformations under dynamic loading or thermally-activated mechanisms, where the competition between various deformation mechanisms is accounted for within the current comprehensive model approach.

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Section: Fracture-induced Twinning In Single Crystal Magnesiumsupporting

confidence: 88%

Thermodynamically-consistent derivation and computation of twinning and fracture in brittle materials by means of phase-field approaches in the finite element method

Amirian,

Jafarzadeh,

Abali

et al. 2022

Preprint

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show abstract

“…In this way, we demonstrate a simple yet effective approach on how to determine the mobility parameter. Moreover, insights in growth rates are of interest given the limited available data [27] and studying these behaviors is vital in high-rate applications of magnesium [76]. Our presented results are then validated in terms of twin area fraction and global shear stress (Fig.…”

mentioning

confidence: 70%

“…However, knowledge gaps in understanding twin growth [24], thickening [25], and interactions [26] need to be addressed before the adoption of magnesium-based alloys into these applications; these are studied herein for a single crystal Mg material system. Ample experimental measurements exist on time-resolved twin evolution in magnesium [27]. In situ data is limited effected by the limitations in available diagnostics to capture growth and evolution behaviors at sufficient length and time scales [28].…”

mentioning

confidence: 99%

Phase-field approach to evolution and interaction of twins in single crystal magnesium

et al. 2022

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Crack initiation and propagation as well as abrupt occurrence of twinning are challenging fracture problems where the transient phase-field approach is proven to be useful. Early-stage twinning growth and interactions are in focus herein for a magnesium single crystal at the nanometer length-scale. We demonstrate a basic methodology in order to determine the mobility parameter that steers the kinetics of phase-field propagation. The concept is to use already existing molecular dynamics simulations and analytical solutions in order to set the mobility parameter correctly. In this way, we exercise the model for gaining new insights into growth of twin morphologies, temporally-evolving spatial distribution of the shear stress field in the vicinity of the nanotwin, multi-twin, and twin-defect interactions. Overall, this research addresses gaps in our fundamental understanding of twin growth, while providing motivation for future discoveries in twin evolution and their effect on next-generation material performance and design.

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“…When driven at high rates, twin boundary dynamics in ferroelectrics, [ 21–23 ] FSMA, [ 24–26 ] Ni, [ 27 ] and Mg [ 28,29 ] were found to follow kinetic relations that are determined by lattice barriers for the twin boundary motion. Nevertheless, part of the studies have reported a significant scattering of the measured velocities at a given value of the electric or magnetic field, [ 23–26 ] indicating that twin boundary dynamics at high rates displays a jerky motion, as well.…”

Section: Introductionmentioning

confidence: 99%

Tracking Twin Boundary Jerky Motion at Nanometer and Microsecond Scales

Bronstein

Tóth

Daróczi

et al. 2021

Adv Funct Materials

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The jerky motion of twin boundaries in the ferromagnetic shape memory alloy Ni-Mn-Ga is studied by simultaneous measurements of stress and magnetic emissions (ME). A careful design of the experimental conditions results in an approximately linear relationship between the measured ME voltage and the nm-scale volumes exhibiting twinning transformation during microsecondscale abrupt "avalanche" events. This study shows that the same distributions of ME avalanches, related to features of jerky twin boundary motion, are found both during and between stress drop events. Maximum likelihood analysis of statistical distributions of several variables reveals a good fit to power laws truncated by exponential functions. Interestingly, the characteristic cutoffs described by the exponential functions are in the middle of the distribution range. Further, the cutoff values can be related to the physical characteristics of the studied problem. Particularly, the cutoff of amplitudes of ME avalanches matches the value predicted by high rate magnetic pulse tests performed under much larger driving force values. This observation implies that avalanches during slow rate twin boundary motion and velocity changes observed by high rate tests represent the same behavior and can be described by the same theory.

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The mechanics of dynamic twinning in single crystal magnesium

Cited by 44 publications

References 29 publications

Thermodynamically-consistent derivation and computation of twinning and fracture in brittle materials by means of phase-field approaches in the finite element method

Thermodynamically-consistent derivation and computation of twinning and fracture in brittle materials by means of phase-field approaches in the finite element method

Phase-field approach to evolution and interaction of twins in single crystal magnesium

Tracking Twin Boundary Jerky Motion at Nanometer and Microsecond Scales

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