Growth mechanism of intergranular creep cavities in α-brass

Abstract

Intergranular cavities were introduced to an α-brass by gas bubble precipitation during simple stress-free annealing. The growth rates of these cavities during creep at a temperature of 700 K and stresses of 5 to 43 MN m⁻² were measured by scanning electron microscopy. The results were consistent with cavity growth being controlled by grain-boundary diffusion. Time-to-fracture measurements indicated that grainboundary diffusion-controlled cavity growth was the time-dominant step in the overall creep fracture process for stresses of 10–30 MN m⁻². At higher stresses the time to fracture was reduced by the formation and propagation of multifacet intergranular cracks during the final stages of the creep life.