Ageing response of cold-rolled Al–Cu–Mg alloy

Abstract

This work presents a detailed investigation of the ageing behaviour of AA2519 alloy subjected to cold rolling with reduction of 10-80% (ε~0.11-1.61). The impact of pre-straining level and ageing duration on the mechanical performance was elucidated via hardness and tensile testing, DSC and analytical TEM. The increasing rolling reduction followed by ageing reduces the peak age hardening and pronounces softening under overageing. This effect of pre-strain on mechanical properties is related to the dependence of a dispersion of plateshaped precipitates that form on the {001} α and {111} α planes on deformation structure. The results show that prior plastic strain profoundly changes kinetics of the ageing reaction and precipitation sequence. The peak age hardening is provided by the dense and homogeneous precipitation of a θ 0 -phase, while the over-ageing is attribute to the concurrent precipitation of the θ-phase on boundaries and thickening θ 0 -phase plates on dislocations. In addition, an Ω-phase platelets appear during ageing; however, its number density is insufficient to affect the mechanical properties, significantly.

Unusual ageing behaviour of friction-stir welded Al–Cu–Mg alloy

“…Moreover, the selected-area diffraction (SAED) pattern taken from this area additionally exhibited the intensity maxima at 1/3 and 2/3 [220] α (red circles in the insert in Fig. 2a) attributable to the Ω-phase [16][17][18][19]. The TEM micrograph taken from the <011> α direction (Fig.…”

“…pct.). This is a typical heat-treatable alloy whose precipitation path is studied relatively well [16][17][18][19]. The material was produced by ingot casting, homogenized at 510 � C for 24 h and then recrystallized by rolling at 425 � C to a true strain of 0.88.…”

“…Such structures are normally observed in frictionstirred aluminum alloys and are usually ascribed to the dynamic recrystallization occurring during FSW [1,2]. Thus, the fine-grained recrystallized microstructure evolved in the stir zone was distinctly different from the coarse-grained, heavily deformed base material [18]. This leads to essentially different precipitation behaviour during subsequent ageing treatment.…”

“…In the diffraction pattern in (a), the reflections from the θ 0 -, θ 00 -and Ω-phases are exemplified by green arrow, blue arrows and red circles, respectively (in greater details, the interpretation of the diffraction pattern is described in Ref. [16][17][18]). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)…”

Influence of θ′ Phase Cutting on Precipitate Hardening of Al–Cu Alloy during Prolonged Plastic Deformation: Molecular Dynamics and Continuum Modeling

“…Cutting of θ phase was also observed in molecular dynamics (MD) studies using realistic models of interatomic interaction [33][34][35]. Depending on the aging conditions, the size of released θ precipitates can vary significantly, starting from a few nanometers in diameter and reaching hundreds of nanometers [23,32,36,37]. In the experimental work [32], it was shown that the cutting of θ phase has a threshold character: cutting of particles only with a size less than 60 nm was observed.…”