Creep behavior of copper at intermediate temperatures—II. Surface microstructural observations

Abstract

Detailed microstructural observations reveal the formation of three types of slip features during creep of copper at intermediate temperatures between 0.46–0.72 Tm, where Tm is the absolute melting point. Single slip occurs at the higher temperatures and lower stresses with the slip lines being inhomogeneously distributed among the grains at the lower strains. Complex wavy slip features are observed at the higher temperatures, higher stresses and with increasing strains, thereby suggesting that cross-slip mechanisms may be important under these conditions. The absence of these slip patterns at the lower temperatures and higher stresses, when mainly multiple slip morphologies are observed, suggests that cross-slip mechanisms are likely to control the creep of polycrystalline copper only in a limited range of stresses and temperatures.