EBSD study of superplastically strained Al-Mg-Li alloy

Abstract

In this study, electron back scatter diffraction (EBSD) was employed to examine the microstructure evolved during superplastic deformation of advanced Al-Mg-Li alloy. In contrast to the widelyaccepted conception of superplasticity, the microstructure was found to be characterized by elongated grains, a notable fraction of low-angle boundaries, and a distinct (though a very weak) crystallographic texture. All these observations suggested a significant activity of intragranular slip.

EBSD study of superplasticity: New insight into a well-known phenomenon

“…This observation implied the evolution of substructure and hence substantial dislocation activity. This finding is in agreement with several previous works in the scientific literature [10,[45][46][47][48][49][50][51][52][53][54][55][56][57]70]. In the present research, the most pronounced levels of KAM were often seen near grain boundaries and at triple joints (Fig.…”

“…As described below, the observed strain hardening was associated with extensive intragranular slip activity and/or dynamic grain growth, thus being in the line with previous results reported in the literature [e.g. 1,[45][46][47][48][49][50][51][52][53][54][55][56][57]. Furthermore, steady-state flow was not observed.…”

“…These observations suggested that the apparentlyequiaxed microstructure may have originated from the transverse subdivision of elongated grains, i.e., via a progressive process such as continuous dynamic recrystallization (CDRX). Such observations and conclusions imply that extensive intragranular slip occurred, as has been suggested by other data in the literature [45][46][47][48][49][50][51][52][53][54][55][56][57].…”

“…Clear signs of extensive intragranular slip have also been found in superplastically-strained materials with "ideal" fine-grain, well-recrystallized microstructures [10,[45][46][47][48][49][50][51][52][53][54][55][56][57]. Specifically, pronounced continuous recrystallization has been observed in various structural materials including aluminum alloys [10,46,47,50,54,55,57], titanium alloys [48,49,51,53], magnesium alloys [52,56], and duplex stainless steel [45]. In two-phase materials, this effect is sometimes attributed to strain partitioning between the softer and harder phases [58].…”

A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

“…The role of the secondary particles on the superplastic behavior is follows. The well-known superplastic deformation mechanisms are grain boundary sliding, dislocation and diffusional creep [ 10 , 73 , 74 , 75 , 76 , 77 , 78 ]. Due to the diffusion-controlled nature of these mechanisms, the superplasticity is usually observed at elevated temperatures and low strain rates.…”