Densification strain rate in sintering of Tho2 and ThO2-0.25% Nb2O5 pellets

The densification behavior of ThO2 and ThO2 containing 0.25%Nb2O5 powder compacts was studied with the help of a high temperature push-rod type dilatometer. From the temperature versus density plots, densification strain rate, (1/ρ)(dρ/dt), were calculated. It was observed that the addition of Nb2O5 to ThO2 has caused a drastic increase in densification strain rate in the density range of 76 to 82% of T.D. A five-fold increase in the values of strain rate for ThO2-0.25%Nb2O5 in comparison to pure ThO2 was observed in the temperature range of 1300 to 1350oC. The decrease in the densification strain rate for ThO2- 0.25% Nb2O5 (composition in wt%) at high densities may be attributed to the grain size effect

Refinement of master densification curves for sintering of titanium

An approximate master curve for the densification of cold-pressed titanium powder during vacuum sintering was published previously. It was based on the combined results for three different titanium powders. The master densification curve model incorporates the effects of particle size, compaction pressure, sintering time, and sintering temperature on densification. The collection of a large amount of additional data now allows refinement of the model. Distinct curves are presented for three different titanium powders, prealloyed Ti6Al4V, and Ti-Ni binary alloys. The master densification curve is sigmoidal, but deviates from the ideal form at high sintered density; the relative sintered density saturates at 90 to 100 pct, depending on the particle size of the titanium powder, and to a lesser extent the compaction pressure. The master densification curve below the saturation level is slightly dependent on the compaction pressure. © 2010 The Minerals, Metals & Materials Society and ASM International