Dynamic strain loading of cubic to tetragonal martensites

Ahluwalia, Rajeev; Lookman, Turab; Saxena, Avadh

doi:10.1016/j.actamat.2005.12.040

Cited by 58 publications

(50 citation statements)

References 23 publications

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“…20,21 Moreover, computer simulations of the mechanical response of a strain-driven martensitic system also show a yield point. 22 For the stress-driven experiment there is a deviation of the pure elastic behavior well below the yield stress. This effect is due to the nucleation of a set of very thin martensitic plates all over the sample, as illustrated by the micrograph in Fig.…”

Section: Resultsmentioning

confidence: 99%

Hysteresis in a system driven by either generalized force or displacement variables: Martensitic phase transition in single-crystallineCu−Zn−Al

et al. 2007

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We report on experiments aimed at comparing the hysteretic response of a Cu-Zn-Al single crystal undergoing a martensitic transition under strain-driven and stress-driven conditions. Strain-driven experiments were performed using a conventional tensile machine while a special device was designed to perform stress-driven experiments. Significant differences in the hysteresis loops were found. The strain-driven curves show reentrant behavior ͑yield point͒ which is not observed in the stress-driven case. The dissipated energy in the stress-driven curves is larger than in the strain-driven ones. Results from recently proposed models qualitatively agree with experiments.

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Section: Resultsmentioning

confidence: 99%

Hysteresis in a system driven by either generalized force or displacement variables: Martensitic phase transition in single-crystallineCu−Zn−Al

et al. 2007

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“…The evolution of the displacements is described by 19,20 ρ ∂ 2 u i (r, t) where ρ is a density, v is the time derivative of the displacements u, and the stresses are given by In each two-dimensional simulation, austenite is quenched to T = 250 K < T m and the system is allowed to transform and equilibrate. The stiff matrix in which the nanosystem is embedded is simulated by fixing the displacements to zero at the boundary (for nanowires there are periodic boundaries along the axis of the wire).…”

Section: Phase-field Modelmentioning

confidence: 99%

Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires

Bouville¹,

Ahluwalia²

2008

Acta Materialia

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We use the phase-field method to study the martensitic transformation at the nanoscale. For nanosystems such as nanowires and nanograins embedded in a stiff matrix, the geometric constraints and boundary conditions have an impact on martensite formation, leading to new microstructuressuch as dots aligned on a square lattice with axes along 01 -or preventing martensite formation altogether. We also perform tension tests on the nanowires. The stress-strain curves are very different from bulk results. Moreover, they are weakly affected by microstructures -the mechanical response of nanowires with different microstructures may be similar, while nanowires with the same microstructure may have a different mechanical behavior. We also observe that at the transition temperature, or slightly below it, the narrowest wires behave pseudoelastically whereas wider wires are in the memory-shape regime. Moreover the yield stress does not change monotonically with width: it has a minimum value at intermediate width.

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“…At these minima, the symmetric and positive definite strain matrices in the geometrically nonlinear theory are [2,12,26,29]. To fix Φ, a 1 = 10 11 Kg/m/s 2 and a 2 = 0.05 are chosen so that microstructures computed in both models resembled those observed in experiments as closely as possible.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Analytical studies suggest that the ratio β 2 / 2 is important in determining the timescale for metastable states [18,32]. A larger viscosity of β = 0.15 Kg/m/s is used instead of the experimentally measured value of β = 0.015 Kg/m/s [2,33], because the smallest value of 2 is larger than expected. Since the simulations are two dimensional and it has not been possible to fit realistic strain, dissipation and capillarity potentials, only qualitative agreement between computed and experimentally observed microstructure morphology is expected.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Alternative possibilities to give long lived metastable states are anisotropic dissipation and interfacial energy terms. The interfacial energy term we have included, 2 2 |ΔU | 2 , is crude and gives an interface width significantly larger than is observed in most experiments. It is also contentious as to how to interpret such a model as an approximation for atomistically sharp interfaces observed in some martensitic materials.…”

Section: Dolzmann and Müllermentioning

confidence: 99%

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Computations of geometrically linear and nonlinear Ginzburg-Landau mo dels for martensitic pattern formation

Muite

Salman

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract.Computations show that a two dimensional geometrically nonlinear Ginzburg-Landau model with inertia exhibits long lived metastable states, that have martensite domains with split tips and bent needles similar to those observed in NiAl. In comparison, the geometrically linear model quickly relaxes to states with twins which extend all the way across the sample and have only short lived tip splitting and needle bending.

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Dynamic strain loading of cubic to tetragonal martensites

Cited by 58 publications

References 23 publications

Hysteresis in a system driven by either generalized force or displacement variables: Martensitic phase transition in single-crystallineCu−Zn−Al

Hysteresis in a system driven by either generalized force or displacement variables: Martensitic phase transition in single-crystallineCu−Zn−Al

Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires

Computations of geometrically linear and nonlinear Ginzburg-Landau mo dels for martensitic pattern formation

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