Application of microhardness testing for the analysis of powder consolidation processes

Abstract

Consolidation of metal and ceramic powders with or without reinforcements is used extensively to produce structural components for demanding applications such as those involving large stresses or high temperature exposure. Hence, modeling of such processes has received substantial attention. These efforts can be grouped into two major areas of activity: those which are micromechanical and those which are continuum in nature. In the first type of approach, the details of particle-particle interactions and discrete densification and deformation mechanisms such as instantaneous plastic flow, power-law creep, and diffusional flow are treated. Unfortunately these techniques require a large amount of material property data which are often known only approximately and hence can lead to substantial uncertainties in predicted densification rates. The objective of the present work was twofold. The first was to establish that microhardness measurements can be used to estimate the relative density (and hence the density distribution) in porous compacts. This would also enable the experimental validation of numerical simulation models for consolidation processes. The second, and equally important goal, was to demonstrate that hardness data can also be used as a method to determine the stress intensification factor and thus may serve in some respects as a state variablemore » indicative of the local relative density in a partially densified compact.« less