Enhanced grain refinement and microhardness by hybrid processing using hydrostatic extrusion and high-pressure torsion

Piotr Bazarnik , Yi Huang , Małgorzata Lewandowska , T.G. Langdon


An investigation was conducted to examine the microstructure and mechanical properties of an Al-5483 aluminium alloy subjected to a hybrid severe plastic deformation (SPD) process consisting of hydrostatic extrusion (HE) followed by high-pressure torsion (HPT) for up to 10 revolutions. The results are compared with those for samples processed separately by HE or by HPT. Microhardness measurements were taken on cross-sectional planes of the HE billets and on the HPT disks and in addition the microstructures were examined using transmission electron microscopy. The results demonstrate that the hybrid process of HE+HPT induces additional grain refinement when compared with HPT with average grain sizes of ~ 60 and 90 nm, respectively. Also, a significantly higher fraction of high-angle grain boundaries (HAGBs) was present after HE+HPT and the beneficial role of HE pre-processing was also apparent in the microhardness measurements. After the hybrid process, the microhardness saturated at Hv≈255 which is higher than after either HPT (Hv≈235) or HE (Hv≈160). A linear Hall-Petch relationship was maintained for coarse-grained and SPD-processed samples with high fractions of HAGBs (above 70%) while samples with higher fractions of low-angle grain boundaries showed a significant deviation from linearity.
Author Piotr Bazarnik (FMSE / DMD)
Piotr Bazarnik,,
- Division of Materials Design
, Yi Huang - [University of Southampton]
Yi Huang,,
, Małgorzata Lewandowska (FMSE / DMD)
Małgorzata Lewandowska,,
- Division of Materials Design
, T.G. Langdon - [University of Southampton]
T.G. Langdon,,
Journal seriesMaterials Science and Engineering A-Structural Materials Properties Microstructure And Processing, ISSN 0921-5093
Issue year2018
Publication size in sheets0.5
Keywords in EnglishCombinations of SPD, Grain boundary misorientation angles, High-pressure torsion, Hydrostatic extrusion, Microhardness, Ultrafine grains
ASJC Classification2210 Mechanical Engineering; 2211 Mechanics of Materials; 2500 General Materials Science; 3104 Condensed Matter Physics
Languageen angielski
2018 MSEA Bazarnik.pdf 1.91 MB
Score (nominal)35
Score sourcejournalList
ScoreMinisterial score = 35.0, 09-06-2020, ArticleFromJournal
Publication indicators Scopus Citations = 11; WoS Citations = 3; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.943; WoS Impact Factor: 2018 = 4.081 (2) - 2018=4.014 (5)
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