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30 pages, 30961 KiB

Open AccessArticle

Faceting and Twin–Twin Interactions in {1121} and {1122} Twins in Titanium

by Christopher Barrett, Jose Martinez and Mashroor Nitol

Metals 2022, 12(6), 895; https://doi.org/10.3390/met12060895 - 24 May 2022

Cited by 6 | Viewed by 1844

Twin–twin interactions are an important component of the microstructural evolution of hexagonal close-packed metals undergoing plasticity. These interactions are prevalent because of the predominance of twinning due to limited easy slip modes. Despite their importance, the complexities of the atomic-scale behavior of interacting [...] Read more.

Twin–twin interactions are an important component of the microstructural evolution of hexagonal close-packed metals undergoing plasticity. These interactions are prevalent because of the predominance of twinning due to limited easy slip modes. Despite their importance, the complexities of the atomic-scale behavior of interacting twins has limited robust characterization. Using interfacial defect theory, we developed a three-dimensional model of twin–twin interactions, double twinning and other complex interfacial reactions that occur between twins acting on different interface planes. Using molecular dynamics, {1122} and {1121} twins in titanium were activated and produced facets, twin–twin interactions and double twins that we characterized with our model. The results showed excellent agreement between the molecular dynamics results and the model. Surprisingly, some highly ordered and mobile boundaries can be produced by these complex reactions, which could provide important insights for higher scale models of plasticity. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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9 pages, 6821 KiB

Open AccessArticle

Plastic Deformation Mechanism and Slip Transmission Behavior of Commercially Pure Ti during In Situ Tensile Deformation

by Chao Xin, Qi Wang, Junqiang Ren, Yonghong Zhang, Jinping Wu, Jie Chen, Liang Zhang, Biao Sang and Le Li

Metals 2022, 12(5), 721; https://doi.org/10.3390/met12050721 - 24 Apr 2022

Cited by 5 | Viewed by 2004

Abstract

The plastic deformation modes of commercially pure titanium (CP-Ti) were studied using an in situ tensile test monitored by electron-backscatter-diffraction (EBSD) assisted slip trace analysis. The plastic strain was primarily accommodated by prismatic slip, followed by deformation twins and pyramidal slip. The slip [...] Read more.

The plastic deformation modes of commercially pure titanium (CP-Ti) were studied using an in situ tensile test monitored by electron-backscatter-diffraction (EBSD) assisted slip trace analysis. The plastic strain was primarily accommodated by prismatic slip, followed by deformation twins and pyramidal slip. The slip transmission between two adjacent grains was predicted using the geometric compatibility factor

m^{'}

, which influenced not only the degree of stress concentration but also the activity of dislocation slip systems. Stress concentration mainly occurred at GBs with an

m^{'}

less than 0.5 and could be released by the activities of pyramidal slip or deformation twins with high critical shear stress (CRSS). Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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11 pages, 2335 KiB

Open AccessArticle

Using Plane Strain Compression Test to Evaluate the Mechanical Behavior of Magnesium Processed by HPT

by Amanda P. Carvalho, Leonardo M. Reis, Ravel P. R. P. Pinheiro, Pedro Henrique R. Pereira, Terence G. Langdon and Roberto B. Figueiredo

Metals 2022, 12(1), 125; https://doi.org/10.3390/met12010125 - 09 Jan 2022

Cited by 11 | Viewed by 2820

Abstract

There is a great interest in improving mechanical testing of small samples produced in the laboratory. Plane strain compression is an effective test in which the workpiece is a thin sheet. This provides great potential for testing samples produced by high-pressure torsion. Thus, [...] Read more.

There is a great interest in improving mechanical testing of small samples produced in the laboratory. Plane strain compression is an effective test in which the workpiece is a thin sheet. This provides great potential for testing samples produced by high-pressure torsion. Thus, a custom tool was designed with the aim to test 10 mm diameter discs processed by this technique. Finite element analysis is used to evaluate the deformation zone, stress and strain distribution, and the accuracy in the estimation of stress–strain curves. Pure magnesium and a magnesium alloy processed by high-pressure torsion are tested using this custom-made tool. The trends observed in strength and ductility agree with trends reported in the literature for these materials. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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12 pages, 2944 KiB

Open AccessArticle

Phase Composition, Nanohardness and Young’s Modulus in Ti-Fe Alloys after Heat Treatment and High Pressure Torsion

by Alena S. Gornakova, Boris B. Straumal, Andrey A. Mazilkin, Natalia S. Afonikova, Mikhail I. Karpov, Elena A. Novikova and Alexander I. Tyurin

Metals 2021, 11(10), 1657; https://doi.org/10.3390/met11101657 - 19 Oct 2021

Cited by 2 | Viewed by 1734

Abstract

Four titanium-iron binary alloys were studied. They were preliminarily annealed in the (α + β) and (α + TiFe) regions of the Ti-Fe phase diagram. The changes in the phase composition, nanohardness, and Young’s modulus of the annealed alloys before and after high [...] Read more.

Four titanium-iron binary alloys were studied. They were preliminarily annealed in the (α + β) and (α + TiFe) regions of the Ti-Fe phase diagram. The changes in the phase composition, nanohardness, and Young’s modulus of the annealed alloys before and after high pressure torsion (HPT) were investigated. Alloys with high iron content after HPT contain a large fraction of the ω phase. The nanohardness of the material in the middle of the radius of the HPT samples varies in the same range of values between 4.4 and 5.8 GPa, regardless of the preliminary annealing. Young’s modulus is a parameter sensitive to structural and phase changes in the material. After HPT, it increases by a factor of 1.5 after preliminary annealing in the (α + β) region in comparison with that in (α + TiFe) region. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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13 pages, 8600 KiB

Open AccessFeature PaperArticle

Thermoactivated Dislocation Motion in Rolled and Extruded Magnesium: Data of the Low-Temperature Acoustic Experiment

by Pavel Pal-Val, Olena Vatazhuk, Andriy Ostapovets, Lubomír Král and Jan Pinc

Metals 2021, 11(10), 1647; https://doi.org/10.3390/met11101647 - 18 Oct 2021

Cited by 2 | Viewed by 1625

Abstract

Acoustic properties (logarithmic decrement and dynamic Young’s modulus) of commercial grade magnesium have been measured in the temperature range 51–310 K. Two types of magnesium samples have been studied: polycrystalline magnesium rolled at room temperature and subjected to hot extrusion. It is shown [...] Read more.

Acoustic properties (logarithmic decrement and dynamic Young’s modulus) of commercial grade magnesium have been measured in the temperature range 51–310 K. Two types of magnesium samples have been studied: polycrystalline magnesium rolled at room temperature and subjected to hot extrusion. It is shown that the amplitude dependences of the acoustic properties are due to the thermally activated breakaway of dislocations from weak pinning centers. Within the framework of the Indenbom-Chernov theory of thermally activated dislocation hysteresis, the binding energy of the interaction between dislocations and defects was estimated. Furthermore, dependences of the activation energy and activation volume on the applied stress were obtained in the microplastic region. The temperature dependences of the dynamic Young’s modulus are obtained in the amplitude independent region in the temperature range of 51–310 K. Functional form of the Young’s modulus temperature dependences corresponds to the classical concepts of the effect of thermal excitation of electrons and phonons on the elastic properties of crystals. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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7 pages, 2645 KiB

Open AccessArticle

The Orowan Stress Measurement of Twinning Dislocations in Magnesium

by Xiao-Zhi Tang and Ya-Fang Guo

Metals 2021, 11(7), 1020; https://doi.org/10.3390/met11071020 - 24 Jun 2021

Viewed by 1679

Abstract

The interaction between a lattice dislocation and non-shearable precipitates has been well explained by the Orowan bypass mechanism. The calculated additional shear stress facilitates the evaluation of precipitation hardening in metallic alloys. The lack of information about how a twinning dislocation behaves in [...] Read more.

The interaction between a lattice dislocation and non-shearable precipitates has been well explained by the Orowan bypass mechanism. The calculated additional shear stress facilitates the evaluation of precipitation hardening in metallic alloys. The lack of information about how a twinning dislocation behaves in the same scenario hinders our understanding of the strengthening against twin-mediated plasticity in magnesium alloys. In the current study, the bowing and bypassing of a twining dislocation impeded by impenetrable obstacles are captured by atomistic simulations. The Orowan stress measurement is realized by revealing the stick-slip dynamics of a twinning dislocation. The measured Orowan stress significantly deviate from what classic theory predicts. This deviation implies that the line tension approximation may generally overestimate the Orowan stress for twinning dislocations. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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Review

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20 pages, 23134 KiB

Open AccessFeature PaperReview

Twinning in Hexagonal Close-Packed Materials: The Role of Phase Transformation

by Amir Hassan Zahiri, Jamie Ombogo, Mehrab Lotfpour and Lei Cao

Metals 2023, 13(3), 525; https://doi.org/10.3390/met13030525 - 05 Mar 2023

Cited by 3 | Viewed by 4107

Abstract

Twinning is a major mechanism of plastic deformation in hexagonal close-packed (hcp) structures. However, a mechanistic understanding of twin nucleation and growth has yet to be established. This paper reviews the recent progress in the understanding of twinning in hcp materials—particularly the newly [...] Read more.

Twinning is a major mechanism of plastic deformation in hexagonal close-packed (hcp) structures. However, a mechanistic understanding of twin nucleation and growth has yet to be established. This paper reviews the recent progress in the understanding of twinning in hcp materials—particularly the newly discovered phase transformation-mediated twinning mechanisms—in terms of crystallographical analysis, theoretical mechanics calculations, and numerical simulations. Moreover, the relationship between phase transformation-mediated twinning mechanisms and twinning dislocations are presented, forming a unified understanding of deformation twinning. Finally, this paper also reviews the recent studies on transformation twins that are formed in hcp martensite microstructures after various phase transformations, highlighting the critical role of the mechanical loading in engineering a transformation twin microstructure. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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22 pages, 7881 KiB

Open AccessReview

Research Progress on Slip Behavior of α-Ti under Quasi-Static Loading: A Review

by Runqi Zhang, Qinyang Zhao, Yongqing Zhao, Dizi Guo and Yu Du

Metals 2022, 12(10), 1571; https://doi.org/10.3390/met12101571 - 22 Sep 2022

Cited by 4 | Viewed by 1342

Abstract

This paper reviews the dislocation slip behavior of α phase in α, near α and α + β titanium alloys dominated by α-Ti deformation under quasi-static loading. The relation of slip activity, slip transfer, slip blocking, twinning and crack initiation is discussed, mainly [...] Read more.

This paper reviews the dislocation slip behavior of α phase in α, near α and α + β titanium alloys dominated by α-Ti deformation under quasi-static loading. The relation of slip activity, slip transfer, slip blocking, twinning and crack initiation is discussed, mainly combined with in situ tensile technology. The slip behavior in Ti-alloys is analyzed in detail from the aspects of critical resolved shear stress (CRSS), grain orientation distribution and geometric compatibility factor m′. In addition, slip blocking is an important factor of the formation of twins and micro-cracks. The interaction of slip behavior and interfaces is clarified systematically. Finally, the insufficiency of current research, future research directions and key difficulties of study are also discussed. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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15 pages, 4002 KiB

Open AccessFeature PaperReview

The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review

by Boris B. Straumal, Anna Korneva, Alexei Kuzmin, Gabriel A. Lopez, Eugen Rabkin, Alexander B. Straumal, Gregory Gerstein and Alena S. Gornakova

Metals 2021, 11(11), 1881; https://doi.org/10.3390/met11111881 - 22 Nov 2021

Cited by 56 | Viewed by 3869

Abstract

In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms [...] Read more.

In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines T_wmin and T_wmax in the multicomponent HEA phase diagrams. The so-called grain-boundary engineering of HEAs permits the use of GB wetting to improve the HEAs’ properties or, alternatively, its exclusion if the GB layers of a second phase are detrimental. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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53 pages, 34551 KiB

Open AccessReview

A Review on Capturing Twin Nucleation in Crystal Plasticity for Hexagonal Metals

by YubRaj Paudel, Deepesh Giri, Matthew W. Priddy, Christopher D. Barrett, Kaan Inal, Mark A. Tschopp, Hongjoo Rhee and Haitham El Kadiri

Metals 2021, 11(9), 1373; https://doi.org/10.3390/met11091373 - 30 Aug 2021

Cited by 14 | Viewed by 4376

Abstract

Owing to its ability to incorporate Schmid’s law at each integration point, crystal plasticity has proven a powerful tool to simulate and predict the slip behavior at the grain level and the ensuing heterogeneous stress/strain localization and texture evolution at the macroscopic level. [...] Read more.

Owing to its ability to incorporate Schmid’s law at each integration point, crystal plasticity has proven a powerful tool to simulate and predict the slip behavior at the grain level and the ensuing heterogeneous stress/strain localization and texture evolution at the macroscopic level. Unfortunately, notwithstanding substantial efforts during the last three decades, this remarkable capability has not been replicated for materials where twinning becomes a noticeable deformation mechanism, namely in the case of low-stacking fault energy cubic, orthorhombic, and hexagonal close-packed structures. The culprit lies in the widely adopted unphysical pseudo-slip approach for capturing twin formation. While the slip is diffuse, twinning is a localized event that occurs as a drastic burst of a confined number of partial twinning dislocations establishing an interface that pursues growth through a thread of perfect twinning dislocations in the sense of bicrystallography. Moreover, at earlier stages, twin nucleation may require atomic diffusion (Shuffling) and faceting, generally demanding higher stress levels not necessarily on the twin shear plane, while triaxiality at adequate sites might be needed or preferred such as lower grain boundary misorientations or other twin boundaries. Identifying a mathematical framework in the constitutive equations for capturing these twin formation sensitivities has been a daunting challenge for crystal plasticity modelers, which has stalled ameliorating the design of key hexagonal materials for futuristic climate change-related industries. This paper reviews existing approaches to incorporating twinning in crystal plasticity models, discusses their capabilities, addresses their limitations, and suggests prospective views to fill gaps. The incorporation of a new physics-based twin nucleation criterion in crystal plasticity models holds groundbreaking potential for substantial progress in the field of computational material science. Full article

(This article belongs to the Special Issue Theoretical, Computational, and Experimental Studies of Deformation Behavior in HCP Metals)

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