Journal•ISSN: 0026-0681
Metal Science Journal
Taylor & Francis
About: Metal Science Journal is an academic journal. The journal publishes majorly in the area(s): Creep & Grain boundary. It has an ISSN identifier of 0026-0681. Over the lifetime, 316 publications have been published receiving 7821 citations.
Topics: Creep, Grain boundary, Dislocation, Alloy, Deformation (engineering)
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TL;DR: In this article, a grain-boundary sliding and grain rotation mechanism was proposed for superplastic extension of the aluminium-zinc eutectoid, where the strain rate (έ), flow stress (σ), grain size (L), and temperature were related empirically.
Abstract: Superplastic extension of the aluminium–zinc eutectoid results primarily from grain-boundary sliding and grain rotation. The strain rate (έ), flow stress (σ), grain size (L), and temperature (T) are related empirically: ɛ ˙ = K σ 2 L 2 exp [ − U k T ] where K is a constant, K is Boltzmann's constant, and U correlates with the activation energy for grain-boundary diffusion.The following proposed mechanism is quantitatively in agreement with our observations...
299 citations
TL;DR: In this paper, structural ageing characteristics of aluminium alloys containing 2 and 4 wt.-% lithium are reported and thin-film electron microscopy was used to confirm the ordered L12-typestructure of the δ′ and to study the precipitate size and distribution over a range of ageing temperatures.
Abstract: The structural ageing characteristics of aluminium alloys containing 2 and 4 wt.-% lithium are reported. One transition phase (AI3Li, δ′) occurs in the alloy system and time-temperature-transformation curves have been determined for this phase and the equilibrium precipitate. Strengthening in these alloys is associated with δ′ precipitation, the peak hardness increment occurring in the 2% alloy after ageing for 24 h at 200°C (473K). Thin-film electron microscopy was used to confirm the ordered L12-typestructure of the δ′ and to study the precipitate size and distribution over a range of ageing temperatures. At low temperatures the δ′, which has a spherical morphology, is very fine (∼ 0.01 μm at 100°C, 373K) and resists coarsening. Above 200°C (473 K) coarsening is rapid and the process has been analysed using the Lifshits-Wagner theory. The δ′ interfacial energy was estimated to be ∼ 240 erg/cm2 (0.24 J/m2) and the lattice mismatch 0.18%. At and below 60°C (333K), ageing is accompanied by an incre...
222 citations
TL;DR: In this paper, the mechanical properties of several austenitic steels containing γ′ precipitate have been studied and a large increase in proof stress occurs during ageing as a result of particle growth at almost co...
Abstract: The mechanical properties of several austenitic steels containing γ′ precipitate have been studied. A large increase in proof stress occurs during ageing as a result of particle growth at almost co...
217 citations
TL;DR: In this article, a theory of precipitate dissolution has been proposed, in which it is implied that a previous treatment by Thomas and Whelan (Phil. Mag., 1961, 6, 1103), where dissolution was considered to be approximately the reverse of growth, is in error in this assumption.
Abstract: A theory of precipitate dissolution has recently been proposed by Aaron (Metal Sci. J., 1968, 2, 192) in which it is implied that a previous treatment by Thomas and Whelan (Phil. Mag., 1961, 6, 1103), where dissolution was considered to be approximately the reverse of growth, is in error in this assumption. Moreover, the time-dependence of the radius of a dissolving precipitate according to Aaron ( R = R 0 − K D t ) disagrees with that of Thomas and Whelan (dR2/dt = −kD). It is pointed out that the “disagreement” arises because the situations treated are themselves dissimilar. Aaron's result is essentially one-dimensional and is derived from the transient part of the diffusion field in one dimension. The result of Thomas and Whelan is for three-dimensional diffusion a...
183 citations
TL;DR: In this article, the deformation behavior of polycrystalline NiAl of various compositions, and of stoichiometric single crystals with different orientations, has been studied in compression in the temperature range 77-1300° K.
Abstract: The deformation behaviour of polycrystalline NiAl of various compositions, and of stoichiometric single crystals with different orientations, has been studied in compression in the temperature range 77–1300° K. All alloys except the aluminium-rich composition (53 at.-% aluminium) were deformable down to 77°K. Plastic deformation of single crystals was strongly anisotropic. All polycrystals and single crystals exhibited the three-stage temperature-dependence of the yield stress typical of b.c.c. alloys. The main effect of non-stoichiometry was to increase the athermal contribution to the yield stress; the strengthening produced by vacancies (aluminium-rich alloys) was greater than that produced by substitutional atoms (nickel-rich alloys).
169 citations