Evolution Of Twins Research Articles

Effect of low temperature annealing on microstructure and properties of copper foil

Electrodeposited copper foil has a non-equilibrium microstructure, and self-annealing takes place at room temperature. In this paper, the evolution of morphology, texture, and microstructure of copper foil during low-temperature annealing was analyzed. Then the microstructure and properties of copper foil deposited by a thickness of 6 µm electrodeposition were systematically studied. The annealing twin evolution behavior of ultra-thin lithium copper foil during annealing treatment is revealed. The production of twins and recrystallization of copper foil during low-temperature annealing is shown to be driven by the non-equilibrium structure and internal tension of the electrodeposited copper foil. The continual decrease in vacancy concentration is caused by an increase in annealing time. The conductivity of the copper foil is increased by 106.95 % percent by the twinning and the vacancy. The twin effect and altered grain size after annealing can reduce tensile strength by 11.55 % and increase elongation by almost 1.15 times.

Modelling mechanical behaviour of a gradient-microstructured material obtained by surface mechanical attrition treatment accounting for residual stresses

In this work, an austenitic 316 L steel was processed by surface mechanical attrition treatment (SMAT), and the induced gradient microstructure was highlighted by experimental measurements. A combined dislocation density-based and grain size-dependent constitutive model is developed to describe the mechanical behaviour of the gradient-microstructured material. In addition, this model also incorporates the grain size-dependent initial twin distribution and evolution of deformation twinning. Residual stress, initial dislocation density and twins are considered to reconstruct the depth-dependent residual fields induced by SMAT. Furthermore, the evolution of dislocation density and twin volume fraction is described during uniaxial tensile loading. Particular attention is devoted to investigate the effect of residual stress and deformation twinning on mechanical behaviour. Results of finite element simulation showed that the gradient microstructure enhances the yield strength, which is in agreement with previous experimental observations. It was revealed that residual stress significantly weakens the yield strength at the initial deformation stage, whereas it has little influence on the plastic behaviour at large deformation. The assumed grain size-dependent deformation twinning model allows describing the evolution of deformation twinning on gradient microstructure. The deformation twinning increases in relation to increased strain hardening during tensile loading. However, the evolution of twin volume fraction shows almost no twin and no variation of twinning within the nanocrystalline grain region.

Effect of carbon nanotube substrate temperature on the evolution mechanism of microstructure in FeCoNiCrCu coatings

The microstructure and substrate temperature dependence of FeCoNiCrCu high-entropy alloys (HEAs) coatings on carbon nanotube (CNT) surfaces were investigated using experimental and molecular dynamics simulations. It was found that the crystal structure of FeCoNiCrCu underwent the evolution of amorphous, stacking faults (SFs), multiple-fold twins, and columnar grains with an increase in the CNT substrate temperature. When the CNT substrate temperature was less than 800 K, the SFs and microtwin formation was induced by the mismatch stress at the interface of HEAs and CNT. Meanwhile, the refinement of SFs was caused by continuous crossing and cutting of dislocations. When the CNT substrate temperature was greater than 800 K, multiple-fold twin were induced by thermal stress at the surface of HEAs coating. During the evolution of the fivefold twin, the first microtwin was formed from the surface of the HEAs, and the remaining four microtwin growth from the center successively. These results provide a new method to design and control the interface structure between HEAs and CNTs.

Effect of Ca alloying and cryogenic temperature on the slip transmission across the grain boundary in pure Mg

The effect of variable Ca (0.3 and 0.5 (wt%)) and deformation temperature on the microstructure, texture and slip behavior of pure Mg is investigated. The uniaxial compression tests were performed to 5%-strain and till fracture at room (RT) and cryogenic temperature (−150 °C, CT) at the strain rate of 10−3 s−1 along rolling direction. The microstructural observation revealed that all the samples displayed equiaxed microstructure and grain size reduction was observed in Mg-Ca alloys. Compared with the strong basal texture Mg, the weak textured Mg-Ca alloys showed remarkable strength/ductility synergy. The detailed post-mortem analysis showed that all samples displayed significant twinning evolution irrespective of the deformation temperature. The slip transmission maps across the grain boundaries showed basal<a> slip dominated plastic deformation in pure Mg, whereas Mg-0.3Ca and Mg-0.5Ca showed abundant prismatic<a> and pyramidal<c+a> slip activity at both deformation temperatures.

Evolution of dislocations and deformation twins in Ti6321 titanium alloy under contact explosion

TEM is used to examine the microstructural evolution of the Ti6321 titanium alloy during the contact explosion. A certain number of dislocations and deformation twins are observed after the explosion. When the slips of dislocations are blocked, {10–11} twins are generated to meet the deformation. The twin boundary deviates from the twin plane and is parallel to the (0001) plane of the matrix. The slide of dislocations and twinning both play a role in the deformation resulting from the explosion.

Loading-direction dependence of interaction types between different twin variants in AZ31 alloy

ABSTRACT In this research, Loading-direction dependence of interaction types between different twin variants in AZ31 alloy was investigated. The microstructure, twin evolution, and the deformation mechanisms of samples were characterised by quasi-in-situ electron backscatter diffraction. The result showed that during rolling direction (RD)-pre-compression and re-compression, the grains with co-zone twin–twin interaction (Type I) are in the majority, while during RD-pre-compression and transverse direction (TD)-re-compression, the grains with non-cozone twin–twin interaction (Type II) are dominant. Furthermore, the effect of different types of twin–twin interaction on subsequent microstructure evolution is clarified. Our experimental results may provide insights for tailoring different types of twin–twin interaction.

Advancing analytical electron microscopy methodologies to characterise microstructural features in superalloys

Electron backscatter diffraction (EBSD) generally links crystallographic orientation to the microstructure of crystalline materials. EBSD datasets are now commonly used to identify phases, grains, and their orientations using off-the-shelf software, although substantial additional information may be extracted. Due to the lack of commercially available software, advanced analyses are often done manually and provide only localised information, lacking statistical significance. Here we introduce novel automated methodologies for advanced analyses of microstructural features in Ni-based superalloys. Our methodologies provide additional insights into the characteristics of these features and their underlying physical phenomena. We showcase how to correct wrongly indexed γ/γ’ interface artefacts in combined EBSD and energy-dispersive X-ray spectroscopy (EDS) measurements, how to classify recrystallised grains based on their location, how to assess and visualise grain boundary planes, and how to study the evolution of Σ3 twins during hot deformation. We further demonstrate how phase fractions and grain sizes are more accurately determined in combined EBSD-EDS measurements. The classification of recrystallised grains into different groups enables individual analyses, facilitating the straightforward identification of the underlying recrystallisation mechanism. Our grain boundary plane analysis provides insights into the coherence of Σ3 twins and the potential boundary planes of incoherent Σ3 boundaries. The current paper is a tutorial-style guide for these methodologies. The algorithms are made freely available and, although demonstrated here on Ni-based superalloys, can also be applied to other systems.

Digital Twin: Benefits, use cases, challenges, and opportunities

Applications of Digital Twin technology have been growing at an exponential rate, and it is transforming the way businesses operate. In the past few years, Digital Twins leveraged vital business applications, and it is predicted that the technology will expand to more applications, use cases, and industries. The purpose of this paper is to do a literature review and explore how Digital Twins streamline intelligent automation in different industries. This paper defines the concept, highlights the evolution and development of Digital Twins, reviews its key enabling technologies, examines its trends and challenges, and explores its applications in different industries.

Continuous dynamic recrystallization nucleation mechanism and annealing twin evolution with respect to grain growth in a nickel-based superalloy

Continuous dynamic recrystallization nucleation mechanism and annealing twin evolution with respect to grain growth in a nickel-based superalloy

A time-evolving digital twin tool for engineering dynamics applications

This paper describes a time-evolving digital twin and its application to a proof-of-concept engineering dynamics example. In this work, the digital twin is constructed by combining physics-based and data-based models of the physical twin, using a weighting technique. The resulting model combination enables the temporal evolution of the digital twin to be optimised based on the data recorded from the physical twin. This is achieved by creating digital twin output functions that are optimally-weighted combinations of physics- and/or data-based model components that can be updated over time to reflect the behaviour of the physical twin as accurately as possible. The engineering dynamics example is a system consisting of two cascading tanks driven by a pump. The data received by the digital twin is segmented so that the process can be carried out over relatively short time-scales. The weightings are computed based on error and robustness criteria. It is also shown how the error and robustness weights can be used to make a combined weighting. The results show how the time-varying water level in the tanks can be captured with the digital twin output functions, and a comparison is made with three different weighting choice criteria.

Evolution of twins and formation mechanism of special fringes inside nanoscale Cu precipitates in ferritic steel

The evolution of twins and the formation mechanism of special fringes inside the Cu precipitates in ferritic steel were studied on the atomic scale in this paper. The results show that the small Cu precipitate (~ 10 nm) already has the fcc structure at the early stage of aging, without conventional 9R or 3R structure, which may attribute to high Si content. The special fringes in Cu precipitates are formed by the co-diffraction between the precipitate and the Fe-bcc matrix, which have the included angle of 17° with the (101) planes of the matrix. When the precipitate grows to 14 nm, twins begin to appear with a spacing of 6 atomic layers and the included angle of 34° between adjacent twinning layers are formed. The thickness of twinning layers increases significantly with the growth of Cu precipitate, while the quantity of twins increases slightly. In addition, the Cu-fcc precipitate with no twins is formed again after sufficient aging (5 h). The appearance and proportion of fringes depend on the relative size and position between the precipitates and the foil of TEM samples. The results of this study are of great significance for understanding the twinning and structural evolution of Cu precipitate in the ferritic matrix. • The complete fcc structure was found in nanoscale Cu precipitates (10 nm) in ferritic steel. • The growth of Cu precipitates is accompanied by the evolution of twins in the precipitates. • The special fringes in Cu precipitates is formed by the co-diffraction of precipitate and matrix.

Evolution of primary and secondary twins during tensile cyclic loading in magnesium alloy ZM21 by quasi in situ EBSD

Large-scale microscopy at consecutive strains using quasi in situ EBSD was used to monitor the texture evolution in specific areas of extruded magnesium alloy ZM21 samples under cyclic tensile loading-unloading. Twin formation throughout the various cycles is highly dependent on slip and twin activity in the neighboring grains, so slip-trace analysis was conducted to monitor the activity of various slip systems. Slip traces were observed on three different glide planes: prismatic plane, first-order pyramidal plane, and second-order pyramidal plane. Formation of primary (including extension and contraction) twins and secondary twins was investigated in detail by overlapping the EBSD maps after pre-compression and after subsequent tension. Parent grains and twins were classified based on their orientations with respect to the ED (loading direction). The inverse pole figure map for the twins was plotted for the ED to calculate the position of the c-axis for twins. All extension twins that formed under reverse loading were located within 45°–90° of the ED axis, whereas the twins that formed during pre-compression were located within 45° of the ED axis. Extension twins are formed during tension loading perpendicular to the pre-existing twins from pre-compression (which have undergone a detwinning process under load reversal). Twin residues from compression interact with grain boundaries or new twins that have formed within the grains during tensile loading. Such interactions between twins and dislocations can result in damage-accumulation mechanisms which lead to crack initiation.

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

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.

Towards a connected Digital Twin Learning Ecosystem in manufacturing: Enablers and challenges

The evolution of digital twin, leveraged by the progressive physical–digital convergence, has provided smart manufacturing systems with knowledge-generation ecosystems based on new models of collaboration between the workforce and industrial processes. Digital twin is expected to be a decision-making solution underpinned by real-time communication and data-driven enablers, entailing close cooperation between workers, systems and processes. But industry will need to face the challenges of building and supporting new technical and digital infrastructures, while workers’ skills development eventually manages to include the increased complexity of industrial processes. This paper is intended to reach a better understanding of learning opportunities offered by emerging Industry 4.0 digital twin ecosystems in manufacturing. Diverse learning approaches focused on the potential application of the digital twin concept in theoretical and real manufacturing ecosystems are reviewed. In addition, we propose an original definition of Digital Twin Learning Ecosystem and the conceptual layered architecture. Existing key enablers of the digital twin physical–digital convergence, such as collaborative frameworks, data-driven approaches and augmented interfaces, are also described. The role of the Learning Factory concept is highlighted, providing a common understanding between academia and industry. Academic applications and complex demonstration scenarios are combined in line with the enablement of connected adaptive systems and the empowerment of workforce skills and competences. The adoption of digital twin in production is still at an initial stage in the manufacturing industry, where specific human and technological challenges must be addressed. The research priorities presented in this work are considered as a recognised basis in industry, which should help digital twin with the objective of its progressive integration as a future learning ecosystem.

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

A theoretical-computational framework is proposed for predicting the failure behavior of two anisotropic brittle materials, namely, single crystal magnesium and boron carbide. Constitutive equations are derived, in both small and large deformations, by using thermodynamics in order to establish a fully coupled and transient twin and crack system. To study the common deformation mechanisms (e.g., twinning and fracture), which can be caused by extreme mechanical loading, a monolithically-solved Ginzburg–Landau-based phase-field theory coupled with the mechanical equilibrium equation is implemented in a finite element simulation framework for the following problems: (i) twin evolution in two-dimensional single crystal magnesium and boron carbide under simple shear deformation; (ii) crack-induced twinning for 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 a steady-state phase-field approach and validated by available experimental data in the literature. The success of this computational method relies on using two distinct 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 modeling approach.

In situ thermal-microstructure characterization of a phase-transforming alloy satisfying cofactor conditions

We establish an experimental platform to combine the differential scanning calorimetry (DSC) with an in situ observation of microstructure by differential interference contrast microscope (DInM). We carry out the experiment on a phase-transforming alloy Au31Cu24Zn45 that closely satisfies the cofactor conditions - the strongest crystallographic compatibility constraints between phases. We confirm that the phase formation events observed by DInM agree well with the heat exchange profile characterized by DSC. We also observe different morphology of twins evolves differently, depending on the twin spacing. Through the quantitative analysis of various morphological domains in the temporal space, we discover that the scaling law between the twin evolution time and the fineness is linear, by which the characteristic transformation time for single variant martensite can be determined for this compatible martensite alloy as 0.636s.

Digital twin in smart manufacturing

Digital twin creates the virtual model of physical entity in digital way, promotes the interaction and integration of physical world and information world, and builds a reliable bridge for industrial information integration. With the rapid evolution of digital twin, the application of digital twin has found an increasingly wide utilization in smart manufacturing. In view of the practical problems encountered by the current smart manufacturing enterprises, this paper aims to carry out quantitative green performance evaluation of smart manufacturing (GPEoSM) driven by digital twin-based industrial information integration system. Based on the mapping between entity and model of smart manufacturing projects, the integration of digital twin information and the interaction of GPEoSM approach, a GPEoSM framework is constructed. According to the framework, a green performance evaluation case for smart manufacturing project of an air conditioning enterprise is carried out. The result shows that the digital twin driven GPEoSM framework is effective and enhances the green performance evaluation of smart manufacturing.

Digital Twin: Technology Evolution Stages and Implementation Layers With Technology Elements

Digital twin has recently received considerable attention in various industry domains. The digital twin replicates physical objects (e.g., people, objects, spaces, systems, and processes) in the real world into digital objects in the digital world. It also provides various simulations to solve problems in the real world or to improve situational operations. Therefore, the digital twin is a convergence of various technologies, such as advanced machine-learning algorithms, data analytics, super-resolution visualization and modeling, and simulation. Because the digital twin is a complicated technology, a step-by-step implementation that includes many technology elements should be considered to create a digital twin model. In this study, implementation layers are introduced to guide practical implementations of the digital twin. In addition, technology elements were suggested for the presented implementation layers. Because the suggested technology elements include clear technology definitions, various application domains (e.g., energy, transportation, logistics, environment, manufacturing, and smart cities) can easily utilize the introduced implementation layers and technology elements according to the intended purpose. Furthermore, this paper describes the evolution of digital twins. Digital twin technology has evolved continuously since 2002, when the digital twin concept was first introduced. In the described evolution levels, we show the future aspects of digital twin technology, according to the technological evolution direction. Therefore, the digital twin model can be efficiently created by considering the evolution direction and future aspects by using the suggested digital twin evolution levels.

Understanding the Evolution of Digital Twin and its Impact a Topic Modeling Approach

Understanding the Evolution of Digital Twin and its Impact a Topic Modeling Approach

Quasi-in-situ study of the twinning evolution of ZC61 alloy during dynamic ED- ERD compression process

In this study, the evolution of extension twinning in extrusion-shear deformed ZC61 alloy, including nucleation, growth, and detwinning, during two-step interrupted dynamic compression along the extrusion direction (ED) and extrusion radial direction (ERD) was investigated using quasi-in-situ electron backscatter diffraction (EBSD) observation. The results show that numerous extension twins, <a> dislocation slips and <c+a> dislocation slips are activated and some detwinning behavior is observed after the second indirect reverse loading step. Most of the activated extension twins satisfy Schmid's law; however, some low-Schmid factor twins form during the compression processes along both the ED and ERD due to strain accommodation among adjacent twins. The slip trace method can determine specific slip systems initiated during the compression process based on the best match between the Schmid factor calculated using the Euler angle and the observed slip trace.