Quantification and modelling of the microstructure/strength relationship by tailoring the morphological parameters of the T1 phase in an Al–Cu–Li alloy

Dorin, Thomas; Deschamps, A.; Geuser, F. De; Sigli, Christophe

doi:10.1016/j.actamat.2014.04.046

Cited by 241 publications

(73 citation statements)

References 30 publications

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“…This increase can be attributed to the nucleation and growth of the T 1 precipitates. The time for the formation of these precipitates in a pre-deformed microstructure is comparable with formerly published data in similar conditions [9,41]. The weld nugget appears to follow a very different evolution, since in all locations it remains at a low hardness together with a low volume fraction for these characteristic times.…”

Section: Kinetics Of Microstructure and Hardness Evolution During Thesupporting

confidence: 82%

“…The microstructure of the base material is dominated by the presence of T 1 precipitates in the form of very thin platelets, as expected in such an alloy, stretched before ageing and subsequently heat treated at 155°C [41]. The average diameter of the T 1 platelets in the base metal as measured on TEM images is 54 ± 12 nm.…”

Section: Microstructure Distribution and Related Hardness Distributiomentioning

confidence: 98%

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Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

2015

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International audienceThis paper presents a systematic study where the distribution of precipitate microstructures is mapped in the cross-section of a friction stir weld made with an AA2050 Al-Cu-Li alloy in the naturally aged temper, as well as the evolution of this microstructure during subsequent post-welding heat treatment (PWHT). This study is carried out using spatially resolved small-angle X-ray scattering, supported by transmission electron microscopy, differential scanning calorimetry and microhardness mapping. The as-welded microstructure is dominated by solute clusters, while very little precipitation has taken place during the welding operation. During PWHT, the precipitation kinetics in the different zones of the weld is mainly controlled by the local dislocation density inherited from welding, and by the amount of solute available for precipitation, which depends on the volume fraction of welding-induced intermetallics. Pre-deforming the weld before the PWHT results in a very effective strength recovery and a nearly homogeneous distribution of hardness. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

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Section: Kinetics Of Microstructure and Hardness Evolution During Thesupporting

confidence: 82%

Section: Microstructure Distribution and Related Hardness Distributiomentioning

confidence: 98%

Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

2015

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“…The two results do correspond particularly well. In a recent study, Dorin et al [16] have actually shown that the relationship between T 1 precipitate volume fraction and yield strength is almost linear, although the detail of the relationship is more complicated. In conclusion, we have demonstrated a methodology for mapping the precipitation kinetics continuously in a material containing a composition gradient.…”

Section: Saxs Measurementsmentioning

confidence: 99%

“…First, it was assumed that no precipitates were present at the end of the heating ramp (which corresponds also to minimum hardness). Second, the volume fraction was assumed to be stabilized after 100h of ageing based on earlier studies [15,16]. In between, the relative volume fraction was calculated, proportional to the integrated intensity Q o [18].…”

Section: Saxs Measurementsmentioning

confidence: 99%

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A combinatorial approach for studying the effect of Mg concentration on precipitation in an Al–Cu–Li alloy

et al. 2016

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We apply a combinatorial approach to study the influence of Mg concentration on the precipitation kinetics in an Al--Cu--Li alloy using a diffusion couple made by linear friction welding. The precipitation kinetics is monitored in the composition gradient material using simultaneous space and time--resolved in--situ small--angle X--ray scattering measurements during ageing, and the strengthening of the precipitates is evaluated by micro--hardness profiles. This data provides an evaluation of the amount of Mg necessary to promote precipitation of the T 1 --Al 2 CuLi phase. Al--Cu--Li alloys are currently experiencing a strong interest due to their combination of low weight, high strength and high toughness suitable for aerospace applications. In the latest generation of alloys (such as commercialized as AIRWARE®), the main strengthening phase sought is the T 1 phase of bulk composition Al 2 CuLi. The bulk structure of this equilibrium phase was resolved by Van Smaalen et al. [1]. In aluminium, it appears as extremely thin platelets on {111} Al planes with aspect ratio up to 50--100. The structure of this phase embedded in the Al matrix has been resolved in detail by Donnadieu et al. [2] and Dwyer et al. [3]. Since earlier studies, it is known that obtaining an efficient precipitation strengthening in this system requires the addition of dislocations [4,5] and of minor solute elements, out of which the most prominent ones are Mg and Ag [5][6][7]. These elements have been shown to be included in the composition of the nanoscale T 1 phase [8,9]. Recently, atom probe tomography has demonstrated that they segregate to the T 1 /Al interface, and that the Mg atoms are involved in a co--clustering or co--precipitation with Cu, linked with dislocations, very early during the ageing process [10]. Now that the qualitative role of the minor solute elements on the precipitation of T 1 has been evidenced, there is a need to understand what solute content is necessary to obtain the desired effect. In particular, the effect of minor solute element concentration on the precipitation of Cu and Li may be strongly non--linear, and even non monotonous as there may be a competition for solute (especially Cu) from the added Mg atoms that may hinder the formation of T 1 instead of promoting it. A traditional alloy series fabrication with a discrete distribution of minor solute concentrations would be extremely cumbersome and may not evidence some of these non--linear events. Instead, we propose to use a combinatorial approach using compositional gradient materials [11], where the main alloying content is kept constant and one minor solute content is varied. This approach has already been used to study composition effects on precipitation hardening in Al--Cu--Mg alloys [12]. However in this study the composition gradient was created simply by inter--diffusion between two alloys, which restricted the dimension of the concentration gradient zone to a few 100 µm, and left at the interface a brittle oxide layer that prevented any mec...

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Quantification of the Effect of Increased Pre‐Deformation on Microstructure and Mechanical Properties of 2A55 Al–Li Alloy

et al. 2022

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Quantification and modelling of the microstructure/strength relationship by tailoring the morphological parameters of the T1 phase in an Al–Cu–Li alloy

Cited by 241 publications

References 30 publications

Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

A combinatorial approach for studying the effect of Mg concentration on precipitation in an Al–Cu–Li alloy

Quantification of the Effect of Increased Pre‐Deformation on Microstructure and Mechanical Properties of 2A55 Al–Li Alloy

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