Three-dimensional analysis of creep voids in copper by serial sectioning combined with large field EBSD

Abstract

The three-dimensional granular and damage structure of two creep deformed copper specimens has been reconstructed using an improved serial sectioning method combining optical profilometry, scanning electron imaging and backscatter electron diffraction. The reconstructions permitted associating creep voids to grain boundaries and evaluating the damage probability of each grain boundary type. The results indicate that creep damage of oxygen free high conductivity copper is governed by topological factors. Quadruple/grain boundaries have the highest probability of damage followed by two- and three-grain boundaries with decreasing percentages. The damage probability of quadruple and three-grain boundaries increases with decreasing stress due to a larger contribution of grain boundary sliding to void nucleation. The relative frequency of damaged two-grain boundaries increases with stress, suggesting a significant role of creep plasticity and the associated grain boundary ledges. No correlation between void location and the crystallographic orientation of neighbour grains was found.

Keywords:

• Creep damage
• Serial sectioning
• EBSD
• 3D reconstruction

Acknowledgements

The authors acknowledge the help of the electron microscopy laboratory staff at EMSE, Sergio Sao-Joao and Marilyne Mondon. They also acknowledge the fruitful discussions and the comments of their colleague J. H. Driver.