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Twinning in Laves Phases by Synchroshear: Atomic Mechanisms and Compositional Contro

Description: Compression tests between 4.2 and 1273 K, compositional variation and conventional transmission electron microscopy were used to investigate the deformation and twinning behavior of C15 HfV{sub 2}+Nb - based Laves phase alloys. We chose two phase C15/bcc alloys to improve the ambient temperature ductility which has not been found in the single phase Laves intermetallic compound. Transmission electron microscopy revealed that substantial mechanical twinning takes place in the C15 Laves phase mat… more
Date: April 7, 2003
Creator: Luzzi, David E. & Pope, David P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Influence of ordered L1₂ precipitation on strain-rate dependent mechanical behavior in a eutectic high entropy alloy

Description: This article focuses on Al0.7CoCrFeNi, a lamellar dual-phase (fcc + B2) precipitation-strengthenable eutectic high entropy alloy. The back-stresses from the coherent L12 precipitate were insufficient to cause improvement in twin nucleation, owing to elevated twinning stress under quasi-static testing. However, under dynamic testing high density of twins were observed.
Date: April 23, 2019
Creator: Gwalani, Bharat; Gangireddy, Sindhura; Zheng, Yufeng; Soni, V.; Mishra, Rajiv & Banerjee, Rajarshi
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Polymorphic nature of {332} 〈 113 〉 twinning mode in BCC alloys

Description: Article using ab initio calculations and experimental observations to show that {332}<113> twinning can be described as a polymorphic solid-state transformation able to produce either twinned or martensitic structures with a unified transformation path.
Date: March 17, 2022
Creator: Kwasniak, P.; Sun, F.; Mantri, Srinivas Aditya; Banerjee, Rajarshi & Prima, Frederic
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Effect of Microstructure on the Deformation Mechanism of Friction Stir-Processed A₁₀.₁CoCrFeNi High Entropy Alloy

Description: This article reports grain refinement using friction stir processing and a detailed study on the microstructural evolution at various locations in the processed region using scanning electron microscopy, in addition to the effect of grain refinement on the tensile properties and the underlying deformation mechanisms in both coarse-grained and fine-grained materials.
Date: September 15, 2014
Creator: Komarasamy, Mageshwari; Kumar, N.; Tang, Z.; Mishra, Rajiv & Liaw, P.K.
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Role of twinning in the optimization of the grain boundary character distribution

Description: The grain boundary character distribution (GBCD) is a microstructural property that describes the proportions of �special� and �random� boundaries as defined by the coincident site lattice model. Recently, there has been increased attention on determination of the GBCD and manipulation of the relative fractions in the microstructure through thermomechanical processing in order to improve material� s properties like corrosion and creep resistance. Most of the �optimization� treatments reported i… more
Date: January 8, 1999
Creator: King, W E; Kumar, M & Schwartz, A J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Influence of shockwave obliquity on deformation twin formation in Ta

Description: Energetic loading subjects a material to a 'Taylor wave' (triangular wave) loading profile that experiences an evolving balance of hydrostatic (spherical) and deviatoric stresses. While much has been learned over the past five decades concerning the propensity of deformation twinning in samples shockloaded using 'square-topped' profiles as a function of peak stress, achieved most commonly via flyer plate loading, less is known concerning twinning propensity during non-I-dimensional sweeping det… more
Date: January 1, 2009
Creator: Gray, George T., III; Livescu, V.; Cerreta, E. K.; Mason, T. A.; Maudlin, P. J. & Bingert, J. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Crystal Level Model for Phase Transformation Allowing for Large Volume Changes

Description: We present a model for materials undergoing diffusionless structural changes including martensitic phase transformation and twinning, with the phase transformations involving large volume changes. Within a given material element, structural changes induce mass fraction rates between the constituents in the material. Deformation results from both these structural changes and elasto-viscoplastic deformation of the constituents themselves.
Date: April 2, 2003
Creator: Barton, N R; Benson, D J & Becker, R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nucleation and Propagation of Deformation Twin in Polysynthetically Twinned TiAl

Description: Using molecular dynamics simulations, we have studied the deformation of polysynthetically twinned (PST) TiAl at room temperature with a bicrystal model. The simulation cell was pre-strained and thermodynamically relaxed to a criterion that all stress components of the simulation cell have gone to zeros; in this way no dislocations were pre-existed in {gamma}-{alpha}{sub 2} interfaces. A uniaxial compression was then applied along one 1/6&lt;112] direction in the surface. The results show that … more
Date: November 16, 2004
Creator: Zhou, L. G.; Hsiung, L. M. & Huang, H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Embrittlement and Flow Localization in Reactor Structural Materials

Description: Many reactor components and structural members are made from metal alloys due, in large part, to their strength and ability to resist brittle fracture by plastic deformation. However, brittle fracture can occur when structural material cannot undergo extensive, or even limited, plastic deformation due to irradiation exposure. Certain irradiation conditions lead to the development of a damage microstructure where plastic flow is limited to very small volumes or regions of material, as opposed to… more
Date: October 6, 2006
Creator: Wu, Xianglin; Pan, Xiao & Stubbins, James
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Advanced characterization of twins using automated electron backscatter diffraction

Description: This paper describes results obtained using an automated, crystallographically-based technique for twin identification. The technique is based on the automated collection of spatially specific orientation measurements by electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM). The key features of the analysis are identification of potential twin boundaries by their misorientation character, identification of the distinct boundary planes among the symmetrically equivale… more
Date: January 1, 2002
Creator: Wright, S. I. (Stuart I.); Bingert, J. F. (John F.); Mason, T. A. (Thomas A.) & Larson, R. J. (Ryan J.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Determining the DUF55-domain structure of human thymocyte nuclear protein 1 from crystals partially twinned by tetartohedry

Description: Human thymocyte nuclear protein 1 (hTHYN1) contains a unique DUF55 domain of 167 residues (55-221), but its cellular function is unclear. Crystals of DUF55 belong to the trigonal space group P3{sub 1}, but twinning causes the data to approach an apparent 622 symmetry. Two datasets to 2.3 {angstrom} resolution were collected. Statistical analysis confirmed that both datasets were partially twinned by tetartohedry. Tetartohedral twin fractions were estimated. After the structure was determined, o… more
Date: June 6, 2009
Creator: Yu, Feng; Song, Aixin; Xu, Chunyan; Sun, Lihua; Li, Jian; Tang, Lin et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Crystallographically degenerate B2 precipitation in a plastically deformed fcc-based complex concentrated alloy

Description: Article describes the development of bcc-ordered B2 and fcc phases manifested in three different orientation relationships (ORs) in the same microstructure: Kurdjumov–Sachs, Nishiyama–Wasserman and Pitsch.
Date: January 22, 2018
Creator: Choudhuri, Deep; Shukla, Shivakant; Green, Whitley; Gwalani, Bharat; Ageh, Victor; Banerjee, Rajarshi et al.
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Work hardening in metastable high entropy alloys: a modified five-parameter model

Description: Article models work hardening response in TRIP HEAs under tensile deformation, which reflects the hardening due to synergistic activity of multiple deformation mechanisms, using a five-parameter work hardening model.
Date: April 19, 2022
Creator: Haridas, Ravi Sankar; Agrawal, Priyanka; Yadav, Surekha; Agrawal, Priyanshi; Gumaste, Anurag & Mishra, Rajiv
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Mapping hierarchical and heterogeneous micromechanics of a transformative high entropy alloy by nanoindentation and machine learning augmented clustering

Description: Article describes how conventional macromechanical tests provide limited insights into complex hierarchical deformation behavior of a transformative high entropy alloy (HEA). In this work, a high throughput microstructure-micromechanical correlative study is presented by combining high-resolution nanoindentation, site-specific microscopy, and Gaussian mixture model (GMM) clustering.
Date: April 26, 2023
Creator: Dhal, Abhijeet; Haridas, Ravi Sankar; Agrawal, Priyanka; Gupta, Sanya & Mishra, R. S.
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Deformation Twinning in Face-Centered Cubic Metals. Technical Report No. 1

Description: A review is presented of work on deformation twinning in fcc metals. Experiments which prove the existence of deformation twins are described, the characteristics of the twins are reviewed, and the stresses required for their production are analyzed. The dislocation models which have been proposed to account for the nucleation of deformation twins are reviewed. A model is proposed for the propagation of twins. (D.L.C.)
Date: February 1, 1963
Creator: Venables, J. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Twinning mechanism in PrCo{sub 2}C{sub x} magnetic phase

Description: A magnetic rhombohedral PrCo{sub 2}C{sub x} (x=0.05{approximately}0.25) phase (space group R {bar 3} m), which is heavily twinned along the (110) and (211) planes, was identified. The twinning mechanism was explored by analyzing the reduction of crystal symmetry due to the cubic-rhombohedral phase transformation. The origin of the twinning and the formation of four twin variants were attributed to the insertion of carbon interstitials into Co{sub 4} tetrahedrons along the {bar 3} axis in the rh… more
Date: July 1, 1997
Creator: Wu, Lijun; Bian, Weimin Bian & Zhu, Yimei
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Twinning in Incommensurate and Commensurate Structures of ReSi{sub 2-x} Alloys

Description: ReSi{sub 2-x} is usually referred to as rhenium disilicide but it actually has a stoichiometry of ReSi{sub 1.75}. Also it is usually described as having the tetragonal MoSi{sub 2}C11{sub b} structure but in fact it exhibits a number of incommensurate and commensurate structures which are based on the C11{sub b} structure. Structure A has an incommensurate periodicity of 4.14a along the a axis. It has a small orthorhombic distortion (b/a {approximately}1.005) accompanied by twinning on the (110)… more
Date: February 1, 1999
Creator: Misra, A. & Mitchell, T.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Micromechanisms of Twin Nucleation in TiAl: Effects of Neutron Irradiation

Description: The so-called radiation-induced ductility (RID) reported in neutron-irradiated 47at%Al alloys is attributed to the formation of effective twin embryos in the presence of interstitial-type Frank loops in {gamma}-TiAl and the subsequent nucleation and growth of microtwins during post-irradiation tensile deformation. The stability of large faulted Frank loops is explained in terms of the repulsive interaction between Shockley and Frank partials. Interaction of only six ordinary slip dislocations w… more
Date: January 28, 1999
Creator: Hishinuma, A. & Yoo, M.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Deformation response of Zr after shock-loading

Description: The post-shock stress-strain response and microstructural evolution of Zr shock-loaded to 7 GPa were investigated. A Bauschinger effect in the room temperature reload stress-strain behavior due to shock-loading has been observed following yielding. Deformation twinning is shown to play a more important role than slip during post-shock plastic deformation and work hardening. The work hardening rate of the shock-prestrained specimens is less temperature sensitive than that of annealed Zr. The und… more
Date: September 1, 1995
Creator: Song, S. G.; Gray, G. T., III & Lopez, M. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dynamic Behavior of Beryllium as a Function of Texture

Description: The high-strain-rate stress-strain responses of commercial hot-pressed beryllium and rolled-sheet beryllium were studied as a function of orientation in compression and room temperature. Hot-pressed beryllium exhibits isotropic mechanical properties; whereas 16:1 rolled sheet was highly anisotropic. Rolled sheet displayed a factor of two difference in strength between the thickness and in-plane (lowest) directions. Twinning is a key deformation mechanism at high rates.
Date: January 5, 1999
Creator: Blumenthal, W. R.; Abeln, S. P.; Mataya, M. C.; Gray, G. T., III & Cannon, D. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Cracking of textured zinc coating during forming process

Description: A model is presented to relate cracking of a zinc coating on steel during forming process with its crystallographic texture. There are three deformation modes that can accommodate strains in a zinc coating caused by external loadings; basal slip, twinning, and cleavage cracking. Twinning of a zinc hexagonal crystal induces a contraction along its c-axis while cleavage relaxes tensile strain along its c-axis. Because of this, when basal slip in grains of a textured zinc coating is difficult unde… more
Date: September 1, 1993
Creator: Mei, Z. & Morris, J. W. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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