Effect of mechanical milling on nanocrystalline grain stability and properties of Cu–Al2O3 composite prepared by thermo-chemical technique and hot extrusion

•The Cu–Al2O3 powder was prepared by thermo-chemical route and mechanical milling.•The additional milling is a novel step in the Cu–Al2O3 powder preparation.•The milling uniformly disperses fine Al2O3 particles in the nanocrystalline Cu.•The dispersed particles effectively strengthen matrix nano-gra...

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Bibliographic Details
Published in:Journal of alloys and compounds 2015-01, Vol.618, p.204-209
Main Authors: Ďurišinová, Katarína, Ďurišin, Juraj, Orolínová, Mária, Ďurišin, Martin, Szabó, Juraj
Format: Article
Language:English
Subjects:
Mechanical milling
Mechanical properties
Microstructure
Nanocrystalline copper composite
Oxide dispersion strengthening
Thermal stability
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Summary:•The Cu–Al2O3 powder was prepared by thermo-chemical route and mechanical milling.•The additional milling is a novel step in the Cu–Al2O3 powder preparation.•The milling uniformly disperses fine Al2O3 particles in the nanocrystalline Cu.•The dispersed particles effectively strengthen matrix nano-grains up to 900°C. In this study, an influence of mechanical milling on the structural characteristics, mechanical properties and electrical conductivity of the ultrafine Cu–3vol.% Al2O3 composite is analyzed. The initial Cu–Al2O3 powder was prepared by in situ thermo-chemical technique. Compared are two samples prepared by compacting of the non-milled and the intensively milled powder. The milling process ensured additional powder refinement and uniform distribution of secondary nano-particles in the Cu matrix. In the process of hot extrusion and annealing of the compact at elevated temperatures, the particles effectively strengthened crystallite/grain boundaries. Therefore, the composite has a homogeneous, thermal stable nanostructure up to 900°C, good hardness of 130HB and yield strength of 235MPa. The composite prepared from the non-milled powder is characterized by a bimodal grain size microstructure, low hardness of 80HB, lower yield strength of 185MPa and it is structurally stable only up to 200°C as a consequence of recrystallization processes and grain growth. The electrical conductivity of both materials is sufficient for electrotechnical applications.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2014.08.177