THERMAL STABILITY OF NANOSTRUCTURE OF DISPERSION STRENGTHENED COPPER ALLOYS

1 ĎURIŠIN Juraj
Co-authors:
1 ĎURIŠINOVÁ Katarína 1 OROLÍNOVÁ Mária
Institution:
1 Institute of Materials Research of Slovak Academy of Sciences, Kosice, Slovakia, EU
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1429-1432
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
306 views / 124 downloads
Abstract

The ultrafine Cu–3 vol.% Al2O3 and Cu–3 vol.% MgO powders with comparable nanocrystalline structures were prepared by thermo-chemical technique and mechanical milling followed by hot extrusion. The study compares an influence of the two different oxide dispersoids on strengthening of the copper matrix after thermo-deformation consolidation of the powders into bulk compacts and annealing of the compacts at elevated temperatures. The as-extruded Cu–Al2O3 alloy exhibits a homogeneous, thermal stable nanostructure up to 900 °C due to the dispersed alumina nano-particles that effectively strengthen crystallite / grain boundaries and inhibit grain growth. In the Cu–MgO material, the MgO particles are less efficient barriers against the grain growth due to their agglomeration into coarser particles (>50 nm) during the consolidation. A negative role here is a weak coherence of particle / matrix interface. The as-extruded Cu – MgO alloy is characterized by a bimodal grain size microstructure, a low hardness and it is structurally stable only up to 200 °C due to the recrystallization processes. The results indicate that the choice of a suitable dispersoid for the given matrix is one of the deciding factors for thermal stabilization of the nano-grains.

Keywords: dispersion strengthening, Cu–Al2O3, Cu–MgO, nanostructure, thermal stability

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