Precipitation Hardening in the First Aerospace Aluminum Alloy: The Wright
            <i>Flyer</i>
            Crankcase

Gayle, Frank W.; Goodway, Martha

doi:10.1126/science.266.5187.1015

Cited by 115 publications

(34 citation statements)

References 7 publications

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“…Age hardening in aluminium alloys, which involves the growth of extremely fine structures ranging from a few atomic layers to precipitates as large as a few hundred nanometres, is a process over hundred years old 1, 2 , and has been successfully applied on an industrial scale to strengthen light-weight metal alloys 3, 4 . During age-hardening, a metal alloy is heated to an elevated temperature to form a completely homogeneous solid-solution and then rapidly cooled to room temperature ( quenching ) to form a super-saturated solid-solution.…”

Section: Introductionmentioning

confidence: 99%

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Liu

Malladi

et al. 2017

Sci Rep

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Age-hardening in Al alloys has been used for over a century to improve its mechanical properties. However, the lack of direct observation limits our understanding of the dynamic nature of the evolution of nanoprecipitates during age-hardening. Using in-situ (scanning) transmission electron microscopy (S/TEM) while heating an Al-Cu alloy, we were able to follow the growth of individual nanoprecipitates at atomic scale. The heat treatments carried out at 140, 160, 180 and 200 °C reveal a temperature dependence on the kinetics of precipitation and three kinds of interactions of nano-precipitates. These are precipitate-matrix, precipitate-dislocation, and precipitate-precipitate interactions. The diffusion of Cu and Al during these interactions, results in diffusion-controlled individual precipitate growth, an accelerated growth when interactions with dislocations occur and a size dependent precipitate-precipitate interaction: growth and shrinkage. Precipitates can grow and shrink at opposite ends at the same time resulting in an effective displacement. Furthermore, the evolution of the crystal structure within an individual nanoprecipiate, specifically the mechanism of formation of the strengthening phase, θ′, during heat-treatment is elucidated by following the same precipitate through its intermediate stages for the first time using in-situ S/TEM studies.

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Section: Introductionmentioning

confidence: 99%

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Liu

Malladi

et al. 2017

Sci Rep

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“…The main hardening phases of this system are θ ′′ and θ ′ , with structures more similar to the fcc-Al lattice than to the equilibrium precipitate phase θ [3]. The aluminium crank case used in the first flight by the Wright brothers was investigated with modern methods two decades ago and was found to contain a high density of Guinier-Preston-zones [4] and a few θ ′ precipitates [5]. The θ ′′ phase, sometimes called GPII, is a curious constellation of {001} Al planes with Al substituted by Cu, spaced 808 pm (four Al planes) apart, making its composition Al 3 Cu [6].…”

Section: Introductionmentioning

confidence: 99%

Structural modifications and electron beam damage in aluminium alloy precipitate θ'–AL₂

Wenner

Friis

Marioara

et al. 2015

Philosophical Magazine

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The θ ′ -Al2Cu phase in an Al-4Zn-2Cu-1Mg-0.7Si (wt.%) alloy was investigated by means of scanning transmission electron microscopy. With our specific alloy composition, the phase is often formed with stacking faults on {101} θ ′ and {001} θ ′ planes. The stacking faults on {101} θ ′ planes are often regularly spaced and create a previously unreported superstructure. Structural damage by electron irradiation is observed, even at a low acceleration voltage of 80 kV. The damage is more pronounced in the θ ′ precipitates with stacking faults, which agrees with theoretical calculations of knock-on scattering cross-sections. These two very different forms of disruptions of the θ ′ structure are linked to its spacious interstitial sites and the ease at which Cu atoms diffuse into and between them.

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“…For a detailed overview of the literature we refer to these papers, and in the present paper we would like to present a more generic overview to evaluate the context in which the term and proposed definitions of "GPB zones" originated and our opinion concerning usage of this term. The use of Al-Cu based alloys that were hardened by nanosized structures goes back at least to 1903 (in the engine that powered the historic Wright brothers flight [10]). The process of age-hardening in Al-Cu based alloys was first discovered in 1909 by Wilm (and published in 1911 [11]) and as early as 1919 the hardening was proposed to arise from clusters of atoms or precipitates [12].…”

mentioning

confidence: 99%

Reply to the comments on “Room-temperature precipitation in quenched Al–Cu–Mg alloys: a model for the reaction kinetics and yield-strength development”

Starink

Cerezo

Yan

et al. 2006

Philosophical Magazine Letters

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Our recent work on Al-Cu-Mg -based alloys with Cu:Mg ratio close to unity showed that the rapid hardening at room temperature and the substantial heat evolution arise from the formation of Cu-Mg co-clusters. Here, it is shown that the measured enthalpy of formation of clusters (~0.3eV per Mg atom) is in reasonable agreement with expectations based on the similarity with Mg-vacancy clusters. The origin of the term GPB zones, as applied to the rapid hardening in Al-Cu-Mg -based alloys, is investigated. It is shown that current knowledge on the nanostucture and microstructure development during rapid hardening can be described without recourse to this alloy-specific term. Analysis of the kinetics of Cu-Mg co-cluster formation by DSC indicates that the formation of CuMg co-clusters during a fast water quench can be sufficiently suppressed to cause substantial nucleation of co-clusters to occur in subsequent natural ageing and artificial ageing at low temperatures.In this reply to [1], which contains some comments on our paper [2], we would like to discuss a number of issues pertinent to points raised by Zahra et al. in the course of their paper. Before we deal with these we first want to note that much of [1] is taken up by a literature review and by a review of calorimetry data, which do not contradict our work. We will not comment on this but we do need to stress that the final interpretation by Zahra et al.[1] "[..] plate-like GPB zones which nucleate on clusters of irregular shape are responsible for the first hardening stage" is inconsistent with our three-dimensional atom probe (3DAP), differential scanning calorimetry (DSC) and hardness data on the two alloys we studied (Al-1.2Cu-1.2Mg and the Al-1.9Cu-1.6Mg (at%)): our 3DAP data shows that neither of these alloys contain substantial numbers of platelet or rod-like structures such as GPB zones during several days ageing at room temperature, whilst the hardness increase and heat evolution is completed within about one day. We will show that all the data and theoretical considerations expressed in [1], as well as data in papers cited in [1], are fully consistent with our conclusions. Specifically we need to note that nowhere in [1], or in any of the papers cited therein, is any nano/microstructural data presented that show platelet or rod-shaped GPB zones within Al-Cu-Mg alloy samples with compositions and heat treatments near the ones we have studied. We believe that there is no conclusive microstructural data having the necessary resolution on Al-Cu-Mg alloys with both Cu and Mg contents in excess of 1at%, heat treated to times up to 5 ×

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Precipitation Hardening in the First Aerospace Aluminum Alloy: The Wright Flyer Crankcase

Cited by 115 publications

References 7 publications

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Structural modifications and electron beam damage in aluminium alloy precipitate θ'–AL₂

Reply to the comments on “Room-temperature precipitation in quenched Al–Cu–Mg alloys: a model for the reaction kinetics and yield-strength development”

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Precipitation Hardening in the First Aerospace Aluminum Alloy: The Wright Flyer Crankcase

Cited by 115 publications

References 7 publications

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy

Structural modifications and electron beam damage in aluminium alloy precipitate θ'–AL2

Reply to the comments on “Room-temperature precipitation in quenched Al–Cu–Mg alloys: a model for the reaction kinetics and yield-strength development”

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Structural modifications and electron beam damage in aluminium alloy precipitate θ'–AL₂