Évolution de la morphologie des pores durant la compression isostatique à chaud de poudres sphériques

Evolution of pores morphology during hot isostatic pressing of spherical powders

¹ Université de Béjaïa, Algérie
² Laboratoire de métallurgie physique, Université de Poitiers

Abstract

Densification by hot isostatic pressing (HIP) of powders induces pore shape transformations governed by several acting mechanisms such as diffusion, creep and plastic yielding. So a HIPing densification description can be described by a systematic study of the morphological evolution of the porous phase. In this way, pore changing shape of superalloy powders are studied on the basis of the stereological and morphological parameters derived from image analysis.

The microstructural study shows that the densification starts by a progressive transformation of the interconnected porosity into isolated pores having an irregular shape. This leads to a large scattering in the pore size. As the process continues, we observe a strengthening in the distribution of the pores size. This is caused by a fragmentation of the largest pores. The final stage of the densification is characterised by a relative homogenization of the pore shape. Pore coalescence can occur in this stage when HIPing parameters does not allow complete densification.