On scaling laws for consolidation of nanocrystalline power compacts

Powder consolidation under load is a common means of forming ceramic or intermetallic components for advanced structural applications. Nanometer sized powders have recently come into use as a means for creating new composite microstructures at the atomistic scale. In addition, powders of this size provide advantages, in general, for powder processing in terms of reduced processing pressures/temperatures and additional control over the final microstructure. However, current models of the deformation processes in powders do not adequately represent the experimental observations in nanosized powder compacts. In this paper, a constitutive model for the consolidation of nanosized powders is proposed. The mechanisms considered include elasticity of the aggregate, diffusion along the interparticle contact area, and relative slip between the particles. The finite element method is used to predict the deformation of a powder compact for a range of loading conditions. A cubic array of cylinders is used to model the compact in a 2-D plane strain situation. Unit cell calculations are performed and scaling laws for the macroscopic response during the deformation of the powder aggregate are.detected in the numerical results.Energy Department 96/04 DE FG 02 91 ER 45439 96/0