Deformation and fracture behavior of new strain-transformable titanium alloys: a multi-scale investigation

Titanium alloys possessing Twinning and Transformation Induced Plasticity effects show promising mechanical properties, particularly high ductility, hardenability, impact and fracture toughness. This work focuses on a strain-transformable, coarse-grained β-Ti-Cr-Sn alloy displaying TWIP effect. To account for the enhanced properties of this alloy, compared to more conventional β-Ti alloys, fracture and deformation features were correlated at different scales. Examinations evidenced a major role of twinning and, more generally, of plasticity-induced phenomena in the ductile fracture process. The resistance of this alloy to plastic deformation (work-hardening), and to crack initiation and propagation is interpreted in view of the progressive, multiscale twinning mechanisms that occur up to the very final stages of fracture.

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Why a Large-Scale Mode Can Be Essential for Understanding Intracellular Actin Waves

Cells ◽

10.3390/cells9061533 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1533 ◽

Cited By ~ 2

Author(s):

Carsten Beta ◽

Nir S. Gov ◽

Arik Yochelis

Keyword(s):

Large Scale ◽

Mass Conservation ◽

Coarse Grained ◽

Cellular Functions ◽

Multi Scale ◽

Spatio Temporal ◽

Actin Waves ◽

Inhibitor Type ◽

Activator Inhibitor Type

During the last decade, intracellular actin waves have attracted much attention due to their essential role in various cellular functions, ranging from motility to cytokinesis. Experimental methods have advanced significantly and can capture the dynamics of actin waves over a large range of spatio-temporal scales. However, the corresponding coarse-grained theory mostly avoids the full complexity of this multi-scale phenomenon. In this perspective, we focus on a minimal continuum model of activator–inhibitor type and highlight the qualitative role of mass conservation, which is typically overlooked. Specifically, our interest is to connect between the mathematical mechanisms of pattern formation in the presence of a large-scale mode, due to mass conservation, and distinct behaviors of actin waves.

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The Role of Deformation Twinning on Creep of Titanium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.121 ◽

2007 ◽

Vol 561-565 ◽

pp. 121-126

Author(s):

Sreeramamurthy Ankem ◽

P. Gregory Oberson

Keyword(s):

Titanium Alloys ◽

Speed Of Sound ◽

Critical Stress ◽

National Science Foundation ◽

Room Temperature ◽

Deformation Twinning ◽

Ti Alloys ◽

National Science ◽

Recent Developments

Normally, deformation twinning is a process that occurs at rates approaching the speed of sound in bulk metals once a critical stress has been reached. However, recently it has been shown that twins grow at speeds many orders of magnitude lower than the speed of sound during room temperature creep of titanium alloys. The net result is that this twinning process can contribute to the low-temperature (less than 0.25*Tm) creep behavior of α, α−β, and β−titanium alloys. For example, α-Ti alloys with small grain size do not extensively deform by twinning and hence show little overall creep strain. These recent developments are reviewed in this paper. This work is funded by the National Science Foundation under Grant Number DMR-0517351.

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Corrosion behavior of titanium alloys in acidic and saline media: role of alloy design, passivation integrity, and electrolyte modification

Corrosion Reviews ◽

10.1515/corrrev-2019-0029 ◽

2020 ◽

Vol 38 (1) ◽

pp. 25-47 ◽

Cited By ~ 1

Author(s):

Michael O. Bodunrin ◽

Lesley H. Chown ◽

Josias W. van der Merwe ◽

Kenneth K. Alaneme ◽

Christian Oganbule ◽

...

Keyword(s):

Corrosion Resistance ◽

Titanium Alloys ◽

Corrosion Behavior ◽

Future Research ◽

Corrosion Resistant ◽

Factors Influencing ◽

Ti Alloys ◽

Service Conditions ◽

Saline Solutions

AbstractThis paper presents an overview of the corrosion behavior of titanium (Ti) alloys in both acidic and saline solutions. The solutions covered in this review are essentially the typical electrolytes encountered by Ti alloys when applied under service conditions. Although Ti alloys are generally known to be corrosion resistant, this review identifies strong reducing acids and fluoride-containing solutions as electrolytes that corrode Ti and its alloys. The pathways that the knowledge of the corrosion behavior of Ti alloys have followed from the 1950s to date are captured in this review. Based on this, the different factors influencing the corrosion behavior of Ti alloys are highlighted and the different research concepts for improving the corrosion resistance of Ti alloys in both solutions are discussed. The limitations of these research concepts are mentioned and the directions for future research are proposed.

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The stochastic tetrad magneto-hydrodynamics via functional formalism

Journal of Plasma Physics ◽

10.1017/s0022377815001105 ◽

2015 ◽

Vol 81 (6) ◽

Cited By ~ 2

Author(s):

Massimo Materassi ◽

Giuseppe Consolini

Keyword(s):

Equations Of Motion ◽

Dynamical Theory ◽

Dynamical Variable ◽

Coarse Grained ◽

Integral Approach ◽

Functional Formalism ◽

Statistical Dynamics ◽

Multi Scale ◽

Lagrangian Variables

In this work we discuss an application of the Tetrad Dynamics approach, a stochastic dynamical theory already introduced in hydrodynamic turbulence, to incompressible magneto-hydrodynamics. This theoretical framework is capable of taking into account some crucial aspects of turbulent plasmas, namely, (i) its material nature, which is stressed through the adoption of Lagrangian variables, (ii) its probabilistic dynamics, which is fundamental to understand the intermittency and highly irregular nature of turbulence, and (iii) the multi-scale character of interactions, which is approached by promoting the space size of parcels to the role of a dynamical variable. In particular, here, we construct the probabilistic equations of motion for quantities describing the evolution of a turbulent plasma (a matrix${\bf\varrho}$describing the parcel’s shape, the plasma velocity and magnetic field coarse-grained gradient tensors,$\unicode[STIX]{x1D648}$and$\unicode[STIX]{x1D652}$), resorting the functional formalism of classical statistical dynamics. Through the introduction of a stochastic action and using a path integral approach, the statistical properties of$({\bf\varrho},\unicode[STIX]{x1D648},\unicode[STIX]{x1D652})$can be derived from those of noises appearing in their equations of motion, both at equilibrium and out of equilibrium.

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Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064669 ◽

1971 ◽

Vol 29 ◽

pp. 122-123

Author(s):

N. E. Paton ◽

D. de Fontaine ◽

J. C. Williams

Keyword(s):

Electron Microscope ◽

Titanium Alloys ◽

Direct Observation ◽

Dark Field ◽

X Ray Diffraction ◽

Resistivity Measurements ◽

Selected Area Electron Diffraction ◽

Ti Alloys ◽

Thin Foils ◽

Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

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An Study of Influence of Imperfections on the Delamination of Diamond-Like Carbon Films

MRS Proceedings ◽

10.1557/proc-719-f8.36 ◽

2002 ◽

Vol 719 ◽

Author(s):

Myoung-Woon Moon ◽

Kyang-Ryel Lee ◽

Jin-Won Chung ◽

Kyu Hwan Oh

Keyword(s):

Cross Sections ◽

Focused Ion Beam ◽

Imaging System ◽

Ion Beam ◽

Carbon Films ◽

Diamond Like Carbon ◽

Glass Substrates ◽

Atomic Force ◽

Initiation And Propagation

AbstractThe role of imperfections on the initiation and propagation of interface delaminations in compressed thin films has been analyzed using experiments with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations have been characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The lengths and amplitudes of numerous imperfections have been measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles has been correlated with the imperfection length.

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