High-Temperature Creep Resistance Resulting from Grain Morphologies in P/M Tungsten Fine Wires

Abstract

The three-dimensional shape of secondary recrystallized grains grown in doped tungsten wires is constructed by an image analyzer. Some grain shape parameters characteristic of grain morphologies are then defined to clarify the morphological effect of grains on the minimum creep rate during diffusional creep without grain-boundary cavitation. While the creep rate decreases as the grain aspect ratio (GAR) increases in the range of GAR 30. The Raj and Ashby's model gives a satisfactory explanation to the former although it does not give the one to the latter. It is proved that their model must be modified using the new grain shape parameters to explain the latter behavior because of the different grain configurations.