Analysis of austenite-martensite phase boundary and twinned microstructure in shape memory alloys: The role of twinning disconnections

Bronstein, Emil; Faran, Eilon; Shilo, Doron

doi:10.1016/j.actamat.2018.11.003

Cited by 23 publications

(11 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both in MD and experiment (see below) Si-I and complex Si-II microstructure form a rational interface which smallest deviation from predicted by crystallographic theory normal is 25.16°. In elasticity-based theory of martensite 15 – 17 , a thin layer of alternating tips of twin-related and variants produce significant elastic energy. Due to very large twinning shear of for Si-II as well as significant deviation of interface from , the elastic energy relaxes by producing an unexpected interfacial nanoband II, consisting of alternating variant of Si-II and strongly deformed and rotated residual Si-I (Fig.…”

Section: Resultsmentioning

confidence: 99%

Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

et al. 2022

View full text Add to dashboard Cite

Crystallographic theory based on energy minimization suggests austenite-twinned martensite interfaces with specific orientation, which are confirmed experimentally for various materials. Pressure-induced phase transformation (PT) from semiconducting Si-I to metallic Si-II, due to very large and anisotropic transformation strain, may challenge this theory. Here, unexpected nanostructure evolution during Si-I → Si-II PT is revealed by combining molecular dynamics (MD), crystallographic theory, generalized for strained crystals, and in situ real-time Laue X-ray diffraction (XRD). Twinned Si-II, consisting of two martensitic variants, and unexpected nanobands, consisting of alternating strongly deformed and rotated residual Si-I and third variant of Si-II, form $$\{111\}$$ { 111 } interface with Si-I and produce almost self-accommodated nanostructure despite the large transformation volumetric strain of $$-0.237$$ − 0.237 . The interfacial bands arrest the $$\{111\}$$ { 111 } interfaces, leading to repeating nucleation-growth-arrest process and to growth by propagating $$\{110\}$$ { 110 } interface, which (as well as $$\{111\}$$ { 111 } interface) do not appear in traditional crystallographic theory.

show abstract

Section: Resultsmentioning

confidence: 99%

Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

et al. 2022

View full text Add to dashboard Cite

show abstract

“…At scales larger than the atomistic scale, twin boundaries lay on preferred crystallographic orientations and tend to move roughly as flat planes. [ 2,8,55 ] The force measurements captured stress drop avalanches with transformed volumes in the range of 5 × 10 −11 m

^{3} \leq V_{normalT}^{normalF} \leq 4 \times 10^{- 9}

m 3 . Such events can be obtained by a motion of the entire twin boundary area ( A TB = 10 −5 m 2 ) as a flat plane for a distance of 5 − 400 μm.…”

Section: Discussionmentioning

confidence: 99%

“…At scales larger than the atomistic scale, twin boundaries lay on preferred crystallographic orientations and tend to move roughly as flat planes. [2,8,55] The force measurements captured stress drop avalanches with transformed volumes in the range of 5 × 10 −11 m ≤ ≤ × − 4 10…”

Section: The Scales Of Twin Boundary Displacements and Energies During Avalanchesmentioning

confidence: 99%

Tracking Twin Boundary Jerky Motion at Nanometer and Microsecond Scales

Bronstein

Tóth

Daróczi

et al. 2021

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…In both cases, the branching appears to be provided by planar interfaces, with (approximately) one half of the original twin band of the minor variant remaining straight and the second half becoming tilted beyond the branching point. Optical micrograph of several branching points in a Ni-Mn-Ga single crystal (courtesy of E. Bronstein; see (Bronstein et al, 2019) for more details on the experiment. )…”

Section: Construction Of the Deformation Gradientsmentioning

confidence: 99%

“…3 is very similar to the real geometry of the branching points observed in shape memory alloys. In Optical micrograph of several branching points in a Ni-Mn-Ga single crystal (courtesy of E. Bronstein; see (Bronstein et al, 2019) for more details on the experiment. )…”

Section: Construction Of the Deformation Gradientsmentioning

confidence: 99%

Branching of twins in shape memory alloys revisited

Seiner

Plucinsky

Dabade

et al. 2020

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

We study the branching of twins appearing in shape memory alloys at the interface between austenite and martensite. In the framework of three-dimensional non-linear elasticity theory, we propose an explicit, low-energy construction of the branched microstructure, generally applicable to any shape memory material without restrictions on the symmetry class of martensite or on the geometric parameters of the interface. We show that the suggested construction follows the expected energy scaling law, i.e., that (for the surface energy of the twins being sufficiently small) the branching leads to energy reduction. Furthermore, the construction can be modified to capture different features of experimentally observed microstructures without violating this scaling law. By using a numerical procedure, we demonstrate that the proposed construction is able to predict realistically the twin width and the number of branching generations in a Cu-Al-Ni single crystal.

show abstract

Analysis of austenite-martensite phase boundary and twinned microstructure in shape memory alloys: The role of twinning disconnections

Cited by 23 publications

References 34 publications

Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

Tracking Twin Boundary Jerky Motion at Nanometer and Microsecond Scales

Branching of twins in shape memory alloys revisited

Contact Info

Product

Resources

About