Densification of porous materials by power-law creep

The densification of a porous intermetallic alloy (Ti-14wt%Al-21wt%Nb) during the final stage of densification has been investigated under various states of stress and compared with the predictions of current models for densification by power-law creep. The experiments generally confirm the model predictions that the densification rate is a sensitive function of the stress state. Experimentally, unconstrained uniaxial compression resulted in the largest densification rates, while constrained uniaxial compression resulted in the lowest. Hydrostatic loading resulted in a densification rate similar (but slightly higher) than that of constrained compression. This ordering of the densification rates agreed well with the model predictions. However, the magnitudes of the measured densification rates are found not to be accurately predicted. A number of factors, including pore shape, pore spatial distribution and matrix microstructure have been observed to affect the densification rate, and the significance of each of these factors to predictive modelling of creep consolidation processes is assessed.