Effect of Microstructure on Properties of Cu-Al2O3

Abstract The progressive Cu- 5 vol. % Al2O3 nanocomposites were produced from powder prepared by original mechanical-chemical method. Powder consolidation was realized by pressing at two different temperatures (at ambient temperature and 400 °C), sintering, forging and extruding. The goal of the work was to compare the influence of the pressing temperatures on the required properties of the compact depending up the material structure. The results of microstructure observations show that in both the materials, the Cu matrix is nanosized with homogeneously distributed very fine γ-Al2O3 secondary particles. The particles pin the dislocations and inhibit the sliding of grain boundaries and strongly retard the recrystallization. The both materials are characterized with excellent thermal stability of structure (until 800 °C) and also with thermal stability of examined properties. The strength of the both materials is high, predominantly thanks grain size strengthening effect and dispersion strengthening effect. However, higher porosity and pores size, as well as their distribution in material pressed at ambient temperature resulted in limited plasticity and low electric conductivity. This porosity is in consequence of weak bonding between the powder particles during the pressing. The pressing at elevated temperature is necessarily for fabrication sufficient dense nanocrystalline material