Microstructural development and tensile strength of an ECAP: deformed Al-4 wt. (%) Cu alloy

Abstract

The tensile strength of metals and alloys can be considerably increased by severe plastic deformation, a consequence of the extreme grain refinement thus achieved. In the present work the deformation was performed by Equal Channel Angular Pressing and the material was an Al-4% Cu alloy. Characterization included tensile tests, and microstructural observation by optical and transmission electron microscopy. After four passes, the yield strength showed an increase of 310% over the undeformed alloy, a figure reduced to 160% by a 250 °C / 1 hour post -deformation anneal. Additionally, the alloy displayed a very low work hardening capacity, especially after the annealing heat treatment. After four deformation passes the grain size of the annealed specimens was estimated to be close to 500 nm. The tensile behaviour and the absence of work hardening were discussed in terms of the fine microstructure.

Predicting grain refinement by cold severe plastic deformation in alloys using volume averaged dislocation generation

“…New data was obtained by performing ECAP on Al-1050, Al-Zr and Al-Zr-Si-Fe alloys and HPT on Al-2024 and Al-3Mg-0.2Mn, TEM and SEM micrographs for several alloys processed by ECAP and HPT are presented in Figs 6-8. Grain size data for a range of other commercial and experimental alloys was obtained from [30,35,36,73,74,75,76,77,78]. The database contains a total of 21 alloys, in a total of 37 alloy-processing combinations, with strains ranging from 1 to 17 and with resulting grain sizes between 2 μm and 50 nm, the full database is presented at [79].…”

“…Hence for Al-1050, Al-1100, Al-97% and Al-3004, which are all thought to contain predominantly β-AlFeSi (Al 5 FeSi) and α-AlFeSi (Al 8 Fe 2 Si), we take r as 50 nm. For the Al-4Cu alloy r was determined from TEM work in [76] as 5 nm. For the Al-7Si and Al-0.5Si alloy r was taken from TEM data in [30] as 13 nm.…”

Archives of Metallurgy and Materials

“…Tensile properties of an ECAP processed Al-5wt%Cu was referred in [20], in which an UTS of 493 MPa with a low elongation to failure value (less than 10%) was achieved after 8 passes. ECAP processing ( four passes) applied to the Al-4Cu alloy allowed to obtain high (UTS) value about 270 MPa and tensile strain about 8% [21]. An age-hardenable 2219 Al-Cu alloy was severely deformed by multidirectional forging (MDF), followed by solution treatment at T8 aging treatment.…”

Precipitation Studies of Undeformed and ECAP-Deformed Al-4%Cu Alloys: Effects on Microstructure and Tensile Properties

“…At first view, this behaviour could be explained by the fact that their raw material was in the as-cast condition, hence containing pores and solidification defects, whilst the Al-4%Cu alloy here employed was subjected to conventional extrusion before ECAP. However, on this respect a previous investigation demonstrated that beyond a certain level of deformation, pores and solidification voids are eliminated, thus restoring the ductility which thereafter increases slightly, possibly because of grain boundary evolution from low to high angle [8]. Said investigation was also performed on Al-4%Cu and showed that four passes are more than sufficient to cause defect closure.…”