scholarly journals Revealing thermally-activated nucleation pathways of diffusionless solid-to-solid transition

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Minhuan Li ◽  
Zhengyuan Yue ◽  
Yanshuang Chen ◽  
Hua Tong ◽  
Hajime Tanaka ◽  
...  
Keyword(s):  
Strain Energy ◽  
Interface Energy ◽  
Colloidal System ◽  
Dislocation Generation ◽  
Thermally Activated ◽  
Transition Pathways ◽  
Particle Level ◽  
Athermal Nucleation ◽  
Dependent Pathway

AbstractSolid-to-solid transitions usually occur via athermal nucleation pathways on pre-existing defects due to immense strain energy. However, the extent to which athermal nucleation persists under low strain energy comparable to the interface energy, and whether thermally-activated nucleation is still possible are mostly unknown. To address these questions, the microscopic observation of the transformation dynamics is a prerequisite. Using a charged colloidal system that allows the triggering of an fcc-to-bcc transition while enabling in-situ single-particle-level observation, we experimentally find both athermal and thermally-activated pathways controlled by the softness of the parent crystal. In particular, we reveal three new transition pathways: ingrain homogeneous nucleation driven by spontaneous dislocation generation, heterogeneous nucleation assisted by premelting grain boundaries, and wall-assisted growth. Our findings reveal the physical principles behind the system-dependent pathway selection and shed light on the control of solid-to-solid transitions through the parent phase’s softness and defect landscape.

Interplay of Strain, Growth Kinetics and Surface Bonding in Growth Modes and Dislocation Generation in Strained Heteroepitaxy

1990 ◽  
Vol 202 ◽  
Author(s):  
C. Snyder ◽  
J. Pamulapati ◽  
B. Orr ◽  
P. K. Bhattacharya ◽  
J. Singh
Keyword(s):  
Growth Kinetics ◽  
Strain Energy ◽  
Critical Thickness ◽  
Dislocation Generation ◽  
3 Dimensional ◽  
Growth Modes ◽  
Atomistic Modelling ◽  
Pseudomorphic Growth

ABSTRACTIn this paper we examine the role of strain and growth kinetics on the growth modes in pseudomorphic growth. Regimes below critical thickness and above critical thickness are examined. Based on atomistic modelling and in-situ RHEED and STM studies we show that a competition between surface chemical energy and strain energy is shown to lead to 3-dimensional blend mode for high strain pseudomorphy. Consequences for dislocation generation are discussed.

Motion of Crystal/Crystal and Crystal/Amorphous Interfaces

1990 ◽  
Vol 183 ◽  
Author(s):  
J. L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Grain Boundary ◽  
Boundary Motion ◽  
High Temperature Annealing ◽  
Thermally Activated ◽  
Transmission Electron ◽  
Grain Boundary Motion

AbstractMotion of ordered twin/matrix interfaces in films of silicon on sapphire occurs during high temperature annealing. This process is shown to be thermally activated and is analogous to grain boundary motion. Motion of amorphous/crystalline interfaces occurs during recrystallization of CoSi2 and NiSi2 from the amorphous phase. In-situ transmission electron microscopy has revealed details of the growth kinetics and interfacial roughness.

Helical Domain Patterns in Tube Configurations: Effect of Geometry Length Scales

2011 ◽  
Vol 172-174 ◽  
pp. 1090-1095 ◽  
Author(s):  
R.H. Zhou ◽  
Qing Ping Sun
Keyword(s):  
Strain Energy ◽  
Optical Measurement ◽  
Strong Support ◽  
Martensite Phase ◽  
Helical Domain ◽  
Self Organized ◽  
Bending Strain ◽  
Strain Martensite ◽  
Tube Geometry

Superelastic NiTi polycrystalline tubes, when subjected to quasi-static stretching, transform from an initial austenite phase to a high-strain martensite phase by the formation and growth of a macroscopic self-organized helical domain as deformation progresses. This paper performed an experimental study on the effects of the externally applied stretching and tube geometry (length L, wall-thickness h and tube radius R) on the martensitic helical domains in the tubes under very slow (isothermal) stretching. The evolution of the helical domains with the applied strain in different tube geometries are quantified by in-situ optical measurement. We demonstrate that the shape of the self-organized helical domain and its evolution are governed by the competition between bending strain energy and domain front energy in minimizing the total energy of the tube system. The former favors a long slim helical domain, while the latter favors a short fat helical domain. The experimental results provide a strong support to the recently developed theoretical relationship.

scholarly journals Measuring impacts of microplastic treatments via image recognition on immobilised particles below 100 μm

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Robin Lenz ◽  
Kristina Enders ◽  
Franziska Fischer ◽  
Josef Brandt ◽  
Dieter Fischer ◽  
...  
Keyword(s):  
Environmental Samples ◽  
Acrylonitrile Butadiene Styrene ◽  
Post Treatment ◽  
Particle Identification ◽  
Particle Level ◽  
Purification Methods ◽  
Analysis Package ◽  
Sodium Polytungstate ◽  
Treatment Procedures

AbstractThe treatment of samples for microplastic (MP) analysis requires purification steps that sufficiently reduce the non-MP content while preserving the targeted particles integrity. Besides their macromolecular structure this also encompasses their in situ numbers and sizes. However, any step of sample manipulation will come at a cost: particle loss, fragmentation, coagulation or degradation may lead to distorted results, predominantly in the smaller fraction of the MP size range. Therefore, the evaluation of MP resistivity against applied methods such as chemical digestions is a vital criterion for obtaining meaningful results on MP content of a sample. We developed a framework to test the applicability of MP purification methods and apply it to four protocols commonly used to prepare environmental samples for MP particle identification. The approach was designed for MP particles being too small to be handled manually (i.e. 10–70 μm). The evaluation consists of a two-tiered assay: a simple particle suspension approach is used to confirm a post-treatment qualitative recognisability of the target polymers by the analysis method of choice (here Raman and FTIR). In a following quantitative part, immobilised particles are used to evaluate the preservation of particle numbers and areas after the treatment on an individual particle level. A Python image analysis package was written that identifies, matches and measures particles on pairs of pre- and post-treatment images, and is available as open source software. Our results show that the chemical digestions using hydrogen peroxide, cooled Fenton’s and a combined alkaline / oxidative treatment using potassium hydroxide and sodium hypochlorite are suitable methods for preparing MP samples for a microspectroscopic analyses. Also acidic sodium polytungstate solution used for MP density separations and a pentane based protocol for lipid removal were found applicable for small sized MP. Certain degradative effects were found when acrylonitrile butadiene styrene is exposed to acidic treatments, as well as for MP from acrylate and epoxy based paint resins in strong oxidative regimes. Several paint resins tested here were spectroscopically not identifiable by polymer attributed bands even before treatment, indicating that these materials might slip through analyses of environmental samples and consequently being underreported. We conclude that evaluating chemical treatment procedures on MP < 100 μm is feasible, despite limitations of the current methodology which we discuss. Our results provide more certainty on the tested methods for MP studies specifically targeting small sizes and should be extended for more protocols used in MP laboratory practises.

scholarly journals Shape of Moving Grain Boundary and its Influence on Grain Boundary Motion in Zinc

2006 ◽  
Vol 249 ◽  
pp. 183-188
Author(s):  
Vera G. Sursaeva ◽  
Boris B. Straumal
Keyword(s):  
Grain Boundary ◽  
Migration Rate ◽  
Activation Enthalpy ◽  
Polarized Light ◽  
Thermally Activated ◽  
Tilt Grain Boundary ◽  
Grain Boundary Motion ◽  
Experimental Runs ◽  
Stationary Shape

The migration of individual special [ ] 0 1 10 tilt grain boundary (GB) with Σ =15 and misorientation angle 29° in Zn bicrystal have been investigated. The stationary shape of migrating GB has been studied and the migration rate has been measured by optical microscopy in situ between 558 and 683 K using polarized light. In certain experimental runs the migrating GB is faceted and moves thermally activated. Its kinetics follows the Arrhenius type dependence despite the fact that shape of moving GB depends on temperature. After detachment from impurity cloud the [ ] 0 1 10 tilt GB migrates activationless in the temperature interval 618÷683 K. The detachment temperature is 618 K. The non-physically high value of the apparent migration activation enthalpy can appear due to the change of GB shape from faceted to smooth and back.

Finite Element Modeling of Grain Aspect Ratio and Strain Energy Density in a Textured Copper Thin Film

1996 ◽  
Vol 436 ◽  
Author(s):  
R. P. Vinci ◽  
J. C. Bravman
Keyword(s):  
Finite Element ◽  
Energy Density ◽  
Aspect Ratio ◽  
Finite Element Modeling ◽  
Strain Energy Density ◽  
Driving Force ◽  
Strain Energy ◽  
Interface Energy ◽  
Element Modeling ◽  
Grain Aspect Ratio

AbstractWe have modeled the effects of grain aspect ratio on strain energy density in (100)-oriented grains in a (111)-textured Cu film on a Si substrate. Minimization of surface energy, interface energy, and strain energy density (SED) drives preferential growth of grains of certain crystallographic orientations in thin films. Under conditions in which the SED driving force exceeds the surface- and interface-energy driving forces, Cu films develop abnormally large (100) oriented grains during annealing. In the elastic regime the SED differences between the (100) grains and the film average arise from elastic anisotropy. Previous analyses indicate that several factors (e.g. elimination of grain boundaries during grain growth) may alter the magnitude of the SED driving force. We demonstrate, using finite element modeling of a single columnar (100) grain in a (111) film, that changes in grain aspect ratio can significantly affect the SED driving force. A minimum SED driving force is found for (100) Cu grains with diameters on the order of the film thickness. In the absence of other stagnation mechanisms, such behavior could cause small grains to grow abnormally and then stagnate while large grains continue to grow. This would lead to a bimodal grain size distribution in the (100) grains preferred by the SED minimization.

The crystallization and growth of AlB2 single crystal flakes in aluminum

1998 ◽  
Vol 13 (12) ◽  
pp. 3485-3498 ◽  
Author(s):  
C. Deppisch ◽  
G. Liu ◽  
A. Hall ◽  
Y. Xu ◽  
A. Zangvil ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Strain Energy ◽  
Misfit Strain ◽  
Homogeneous Distribution ◽  
Temperature Growth ◽  
High Temperature Heat Treatment ◽  
Temperature Heat ◽  
Peritectic Transition ◽  
Temperature Heat Treatment

An in situ high temperature heat treatment was used to investigate the crystallization and growth behavior of AlB2 flakes in aluminum. Aluminum samples containing 1.8% boron were heated above the liquidus and then rapidly cooled through the Al(L) + AlB12 region to avoid the formation of AlB12 crystals. Subsequently, a homogeneous distribution of high aspect ratio AlB2 flakes crystallized upon holding below the peritectic transition temperature. Growth rate in the (a) and (c) dimensions increased during elevated hold temperatures below the peritectic transition temperature. Surprisingly, faster cooling rates from above the liquidus to room temperature resulted in thinner, wider flakes. Similar to graphite this phenomenon is believed to result from a need to accommodate a changing misfit strain energy between the solidifying aluminum and the growing AlB2 flakes.

Tropomyosin-paramyosin system and ‘prolonged contraction’ in a molluscan smooth muscle

1964 ◽  
Vol 160 (981) ◽  
pp. 536-542 ◽  
Keyword(s):  
Slow Relaxation ◽  
Retractor Muscle ◽  
Muscle Fibres ◽  
Colloidal System ◽  
Contraction Phase ◽  
Contractile System ◽  
Molluscan Smooth Muscle ◽  
Anterior Byssal Retractor Muscle

Tonic molluscan muscles such as the anterior byssal retractor muscle of Mytilus ( ABRM ) are outstanding in two respects: First they contain, in even larger amounts than actin and myosin, tropomyosin- A (Bailey 1956; Rüegg 1961 a ) which constitutes a system of filaments, the tropomyosin-paramyosin system (cf. Hall, Jakus & Schmitt 1945; Hanson et al . 1957). Secondly, these muscles are able to maintain tension passively for prolonged periods without fatigue (holding function, catch). The capacity for prolonged (tonic) contraction has been related to the extremely slow relaxation of tonically contracted muscle fibres (Lowy & Millman 1963). During slow relaxation the stretch resistance is high and tension is maintained passively (Johnson & Twarog 1960; Jewell 1959; Lowy & Millman 1963). The slow tension decay after cessation of isometric contraction may then be attributed to the slow breaking of contractile actin-myosin linkages which are assumed to be formed in the preceding contraction-phase (Lowy & Millman 1963). Alternatively Johnson (1962) and Rüegg (1961) suggested that the relaxation of the contractile system is slowed down by a special colloidal system, the tropomyosin-paramyosin system, the stiffness of which was assumed to be increased in the catch and decreased after unlocking the catch with certain types of stimulation, e.g. by addition of serotonin. Subsequently it has been shown that the catch (i.e. serotonin sensitive stiffness) may also be produced in apparently resting ABRM when the muscle is immersed in a solution of increased CO 2 tension (Rüegg & Weber 1963). The caught state may then be regarded as a stretch-resistant state. If the catch is based on the tropomyosin-paramyosin system, tropomyosin- A structures ought to have a capacity to resist stretch and they should have this holding capacity in surviving as well as in glycerol extracted, dead muscle fibres. This possibility has been tested by stretch experiments with surviving and extracted ABRM fibre-bundles after inactivation of the actomyosin contractile system with thiourea. The latter has been shown to be an inhibitor of actinmyosin interaction in vitro (Portzehl 1961; Rüegg 1961 b ) and since it penetrates readily into muscle fibres, we have applied it also in the case of surviving ABRM in an attempt to inactivate the actomyosin system in situ (Rüegg, Straub & Twarog 1963).

Texture Evolution in Cu Films and Lines

2007 ◽  
Vol 990 ◽  
Author(s):  
Chia-Jeng Chung ◽  
David Field ◽  
No-Jin Park ◽  
Christy Woo
Keyword(s):  
Grain Growth ◽  
Strain Energy ◽  
Texture Evolution ◽  
Growth Conditions ◽  
Geometric Constraints ◽  
In Situ Observation ◽  
Processing Conditions ◽  
Cu Films ◽  
Unique Character

ABSTRACTGrain growth in polycrystalline films is controlled by the energetics of the surface, interface and grain boundaries as well as strain energy. The unique character of damascene lines fabricated from electroplated Cu films introduces the additional considerations of bath chemistry and geometric constraints. The moderate stacking fault energy of Cu allows for the development of a substantial twin fraction for certain growth conditions. This paper discusses in-situ observation of grain growth in Cu films and lines under various processing conditions. It is shown that for thicker films and for structures constrained within damascene trenches the energetics of twin boundary formation play a large role in texture development of these structures.

Effect of Plastic Deformation on the Isothermal FCC/HCP Phase Transformation during Aging of Co-27Cr-5Mo-0.05C Alloy

2007 ◽  
Vol 560 ◽  
pp. 23-28
Author(s):  
A. Mani-Medrano ◽  
Armando Salinas-Rodríguez
Keyword(s):  
Plastic Deformation ◽  
Martensitic Transformation ◽  
Tensile Deformation ◽  
Internal Stresses ◽  
X Ray Diffraction ◽  
Thermally Activated ◽  
Prior Plastic Deformation ◽  
Last Stage ◽  
Isothermal Martensitic Transformation

The effects of tensile deformation on the amount of hcp phase formed during a 3 hour isothermal aging at 800 °C is studied using in-situ X-ray diffraction and scanning electron microscopy. It is shown that the start of the isothermal martensitic transformation during aging of this material is delayed by prior plastic deformation. Nevertheless, the total amount of hcp phase present in the microstructure at the beginning of aging increases at a continuously decreasing rate due to stress-assisted transformation. This behavior is attributed to the relieving of internal stresses produced by plastic deformation prior to aging. Finally, during the last stage of aging, the amount of hcp phase in the microstructure increases as a result of isothermal martensitic transformation. It is suggested that the presence of mechanically-induced hcp phase during aging inhibits the thermally activated nucleation process that leads to the isothermal martensitic transformation.

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