Materials Science Forum, Vol.447-4, 55-60, 2003
Comparison between 2D and 3D characterisations of damage induced by superplastic deformation
Damage by cavitation is frequently induced by superplastic deformation of single phase alloys. Characterisation of this damage is usually carried out by quantitative metallurgy on polished sections, leading to the measurement of 2D parameters like the cavity area fraction, the number of cavities per unit area or the cavity areas. However, due to the predominance of grain boundary sliding during deformation, cavities can have very complex shape and consequently the direct interpretation of data deduced from such procedures is delicate. X-ray micro-tomography can provide three dimensional (3D) views of damaged microstructures and consequently, parameters like the number of cavities per unit volume or the volume of each cavity can be easily measured. However, in order to get an appropriate resolution (typically approximate to 1 mum), high resolution X-ray tomography is needed which remains a heavy technique. Consequently, it is interesting to compare data deduced from 2D and 3D in order to identify the parameters for which 2D characterisation is sufficient and those for which 3D techniques are required. This comparison is the main purpose of this paper.