Amorphisation and phase transformations in mechanically alloyed Ti–Al powders: electron microscopy investigation

Bonetti, E.; Cocco, G.; Enzo, Stefano; Valdrè, Giovanni

doi:10.1179/mst.1990.6.12.1258

Cited by 31 publications

(10 citation statements)

References 9 publications

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“…However, the formation of fcc phase can be seen after 4 h milling in the XRD pattern along with the hcp phase, while 6 h milled Ti–6Al–4V–0.5TiC–Hep powder showed only fcc phase. Similar phase transformations from hcp to fcc have been reported in pure titanium and its alloys . However, Ti–6Al–4V–0.5TiC–Sn powders milled for 2 and 4 h showed only hcp phase and did not show any solid state phase transformations.…”

Section: Resultssupporting

confidence: 82%

“…This C and H rich metastable fcc titanium phase is seen to revert back to hcp‐titanium with the simultaneous formation of titanium carbide or titanium hydrocarbide upon annealing at high temperatures . Extension of solid solubilities, formation of compounds and amorphous phases were also observed during high energy ball milling of powder mixtures, such as Ti and Al . Suryanarayana et al studied the phase evolution of Ti–Al alloys containing 24 and 50 at% Al prepared by mechanical alloying (MA).…”

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confidence: 99%

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Phase Evolution during High Energy Cube Milling of Ti–6Al–4V–0.5 vol% TiC Powders Using Heptane and Tin as Process Control Agents (PCAs)

et al. 2017

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(1 of 7) 1770006 CONTENTS The inherently low volume fraction and ordered tessellated organization of lattice materials enables the presented scheme to dramatically change size of lattice materials through simultaneous folding of the walls while preserving the overall shape. The elastic modulus and band gaps are shown to be tunable through the folding process. The proposed concept may be used to fold any arbitrary shape and provides new tools for development of deployable and multifunctional structures. Further details can be found in article 1600646 by Ashkan Vaziri and co-workers. Chiral cellular solids have auxetic effects induced by internal cell rotation. The chirality-induced rotation enables auxetic effects under both small and large deformation. The auxetic effects can be signifi cantly amplifi ed by increasing the internal rotation effi ciency. A new family of chiral cellular composites is developed by adding center cores or softer corner hinges. As proof of concept, the new designs were 3D-printed via multi-material printing. Further details can be found in article 1600609 by Yaning Li and co-workers. Communications Presented is a novel concept to dramatically change size of lattice materials through simultaneous folding of the walls while preserving the overall shape. The elastic modulus and band gaps are shown to be tunable through the folding process. The proposed concept may be used to fold any arbitrary shape and provides new tools for development of deployable and multifunctional structures. For the fi rst time, the concept of amplifying chirality-induced auxetic effect via elevating internal rotation effi ciency is proposed and proved via multi-material 3D printing, mechanical experiments, and fi nite element (FE) simulations. A linear relationship between the internal rotation effi ciency and the Poisson's ratio is discovered. This study provides guidelines to design new chiral cellular solids with robust auxetic effects under large deformation. Bioinspired multifunctional composite of single crystal ceramic platelets and piezoelectric polymer prepared by layer-by-layer approach is described. The composite is transparent, is piezoelectric, and shows large ductility. Effect of the annealing process on the morphology of the polymer phase and on the mechanical properties of the composite is also investigated. The present paper comprehensively investigates the precipitation hardening mechanism in Mg-Nd-Y-Zr-Ca alloy by means of atomic-resolution HAADF-STEM. As shown in the fi gure, a number of complex precipitate structures are unraveled at the atomic scale, which provides new insights into the solid-state phase transformation. In addition, the paper correlates the micro-structural evolution with the mechanical property of the alloy. Experiments show that deformation for diffusion welding with uniaxial pressure depends on aspect ratio and number of bonding planes. For large diameters and small heights deformation decrease. One reason is friction between stamps, possessing a low TEC, and sample. For ...

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Section: Resultssupporting

confidence: 82%

mentioning

confidence: 99%

Phase Evolution during High Energy Cube Milling of Ti–6Al–4V–0.5 vol% TiC Powders Using Heptane and Tin as Process Control Agents (PCAs)

et al. 2017

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“…Furthermore, change in crystal structure was induced primarily due to lattice instability caused by nanocrystallization (grain size reduction), lattice expansion or strain, and negative hydrostatic pressure from the core to the surface of the grains. Besides elements, evidence of such polymorphic transformation by mechanical attrition was earlier reported in Ti-Al alloy [11] and ceramic compounds [12] and alloys [13]. In the present study, we present evidences of polymorphic hcp to fcc transformation in several nanocrystalline Ti-Zr binary alloys and analyze the genesis of this transformation in terms of systematic microstuctural investigation, model based thermodynamic calculation and suitable comparison with earlier relevant studies.…”

Section: Introductionmentioning

confidence: 80%

Hexagonal close packed to face centered cubic polymorphic transformation in nanocrystalline titanium–zirconium system by mechanical alloying

Bera

Manna

2006

Journal of Alloys and Compounds

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“…This places a very stringent requirement on attempts to produce such titanium based materials via an MA processing route. Although there have been numerous small scale investigations of the effects of MA on various titanium based materials [2][3][4][5][6][7][8][9][10][11][12], relatively little attention was paid to the control of this contamination during the MA process and the possible microstructural effects such contamination might have. Therefore, work at the DRA has concentrated on addressing this key requirement, the control of contamination during the MA process.…”

Section: Development Of the Ma Process To Minimise Contaminationmentioning

confidence: 99%

Non-equilibrium synthesis of new materials

Gardiner¹,

Goodwin²,

Dodd³

et al. 1996

Adv Perform Mater

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Over the last few decades it has become apparent that metallic materials produced by conventional casting processes have reached their limit. Some improvements have been obtained by rapidly cooling bulk alloys but major increases have required the development of rapid solidification processes. However, more radical approaches, such as mechanical alloying (MA) and physical vapour deposition (PVD), are also being explored and these are the subject of this paper. This paper describes the physical basis behind the development of MA and PVD in the Structural Materials Centre and presents the results of some materials development programmes on aluminium, magnesium and titanium based materials.

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Amorphisation and phase transformations in mechanically alloyed Ti–Al powders: electron microscopy investigation

Cited by 31 publications

References 9 publications

Phase Evolution during High Energy Cube Milling of Ti–6Al–4V–0.5 vol% TiC Powders Using Heptane and Tin as Process Control Agents (PCAs)

Phase Evolution during High Energy Cube Milling of Ti–6Al–4V–0.5 vol% TiC Powders Using Heptane and Tin as Process Control Agents (PCAs)

Hexagonal close packed to face centered cubic polymorphic transformation in nanocrystalline titanium–zirconium system by mechanical alloying

Non-equilibrium synthesis of new materials

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