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The high strength of structural aluminium alloys depends strongly on the controlled precipitation of specific intermetallic phases, whose identity and crystal structure can be difficult to predict. Here, we investigate the Al-Pt system,…

Materials Science · Physics 2023-06-14 Shenghan Su , Laure Bourgeois , Nikhil V. Medhekar

Nucleation and growth of Ti$_3$Al \textalpha{}$_2$ ordered domains in \textalpha{}-Ti--Al--X alloys were characterised using a combination of transmission electron microscopy, atom probe tomography and small angle X-ray scattering. Model…

Materials Science · Physics 2021-03-22 Felicity F. Dear , Paraskevas Kontis , Baptiste Gault , Jan Ilavsky , David Rugg , David Dye

The Al-Ag system is thought to be a well-understood model system used to study diffusional phase transformations in alloys. Here we report the existence of a new precipitate phase, zeta, in this classical system using scanning transmission…

Materials Science · Physics 2017-05-29 Zezhong Zhang , Laure Bourgeois , Julian M. Rosalie , Nikhil V. Medhekar

An Al-11.3Li-0.11Sc (at. %) alloy was double-aged to induce first alpha'-Al3Sc and then delta'-Al3Li precipitates. Atom-probe tomography revealed both single-phase delta'-precipitates and core-shell alpha'/delta'-precipitates (with…

Materials Science · Physics 2009-11-13 Matthew E. Krug , David C. Dunand , David N. Seidman

The secondary phase, such as Ni$_3$Al-based $L1_2$ $\gamma^\prime$, is crucially important for precipitation strengthening of superalloys. Composition-structure-property relations provide useful insights for guided alloy design. Here we use…

Materials Science · Physics 2023-06-22 Nikolai A. Zarkevich , Timothy M. Smith , John W. Lawson

T-(Al20Cu2Mn3) phase dispersoids are important for limiting recovery and controlling grain growth in Al-Cu alloys. However, these dispersoids can also reduce precipitation hardening by acting as heterogeneous nucleation sites and may lead…

Dwell fatigue, the reduction in fatigue life experienced by titanium alloys due to holds at stresses as low as 60% of yield, has been implicated in several uncontained jet engine failures. Dislocation slip has long been observed to be an…

Additively manufactured (AM) aluminum alloys with high strength and thermal stability have broad applications in turbine engines, vacuum pumps, heat exchangers, and many other industrial systems. Employing precipitates with an L1$_2$…

First principles calculations are used to study the preferential occupation of ternary alloying additions into the binary Ti-Al phases, namely $\gamma$-TiAl, $\alpha_2$-Ti$_3$Al, $\beta_{\mathrm{o}}$-TiAl, and B19-TiAl. While the early…

Materials Science · Physics 2016-06-22 David Holec , Rajeev K. Reddy , Thomas Klein , Helmut Clemens

While lean Mg-Zn-Ca alloys are promising materials for temporary implants, questions remain on the impact of Zn and Ca. In this context, the precipitation in Mg-1.5Zn-0.25Ca (ZX20, in wt.%) was investigated upon linear heating from about…

The phase stability and transformation between hexagonal close-packed (hcp) {\alpha}-phase and body-centered cubic (bcc) \b{eta}-phase in titanium (Ti) alloys are critical to their mechanical properties and manufacturing processes for…

Materials Science · Physics 2025-05-06 Huicong Chen , Chenwei Shao , Zhuocheng Xie , Jun Song , Yu Zou

The alpha/beta interface in Ti-6Al-2Sn-4Zr-6Mo (Ti-6246) is investigated via centre of symmetry analysis, both as-grown and after 10% cold work. Semi-coherent interface steps are observed at a spacing of 4.5 +/-1.13 atoms in the as-grown…

Ti has a high affinity for hydrogen and is a typical hydride formers. Ti-hydride are brittle phases which probably cause premature failure of Ti-alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen…

Atomic scale computer simulations using density functional theory were used to investigate the behaviour of tin in the tetragonal phase oxide layer on Zr-based alloys. The $Sn_{Zr}^{\times}$ site defect was shown to be dominant across most…

Materials Science · Physics 2015-02-25 B. D. C. Bell , S. T. Murphy , P. A. Burr , R. W. Grimes , M. R. Wenman

Aiming at increasing the yield strength of transformation and twinning induced plasticity (TRIP and TWIP) titanium alloys, a dual-phase $\alpha$/$\beta$ alloy is designed and studied. The composition Ti 7Cr 1.5Sn (wt.%) is proposed, based…

Age hardening induced by the formation of (semi)-coherent precipitate phases is crucial for the processing and final properties of the widely used Al-6000 alloys. Early stages of precipitation are particularly important from the fundamental…

Materials Science · Physics 2017-08-29 Daniele Giofré , Till Junge , W. A. Curtin , Michele Ceriotti

Precipitation of the \gamma' (AlAg2) phase was investigated in Al-Ag(-Cu) alloys using high resolution transmission electron microscopy and scanning transmission electron microscopy. Precipitation commenced with segregation of silver to…

Materials Science · Physics 2012-01-09 Julian M. Rosalie , Laure Bourgeois , Barrington C. Muddle

The study of the Cu-Sn-In ternary system has become of great importance in recent years, due to new environmental regulations forcing to eliminate the use of Pb in bonding technologies for electronic devices. A key relevant issue concerns…

Materials Science · Physics 2015-06-04 Gabriela Aurelio , Silvana A Sommadossi , Gabriel J Cuello

We consider the process of precipitation in binary alloys in the presence of mechanical deformation. It is commonly observed that mechanical deformation prior to or during precipitation leads to microstructure with excess defects, which…

Materials Science · Physics 2025-02-11 Alex Mamaev , Duncan Burns , Nikolas Provatas

Titanium is commonly added to nickel superalloys but has a well-documented detrimental effect on oxidation resistance. The present work constitutes the first atomistic-scale quantitative measurements of grain boundary and bulk compositions…

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