FORMATION OF BAINITE IN BETA BRASS.

When quenched from the beta field alpha forms from beta brass in a slow, displacive manner analogous to the formation of bainite in steels. The decomposition product adopts a needle-like morphology at high temperatures and an internally faulted, plate-like morphology at low temperatures. Both forms develop over a narrow range of temperatures and exhibit similar growth rates. Within this transition region, needles nucleate at the edges of plates and also independently at beta grain boundaries and within the grains. Except at temperatures near the alpha betabeta solvus, growth rates are substantially higher than expected from a diffusion controlled growth model and microprobe studies suggest that the degree of solute partitioning becomes less severe as the reaction temperature is lowered. Author