Directional solidification of Pb-Sb alloy assisted by pressure pulses

Abstract

Directional solidification processes assisted with pressure pulses were performed with the goal of producing a novel process capable of introducing changes in dendritic microstructure morphologies. The alloy used in these experiments was a Pb-7wt% Sb, with a liquidus temperature of approximately 280°C. Various melt pressure profiles were investigated with maximum pressures of -266.3 to -1452.8psi and oscillation frequencies ranging from 0 (constant force) to 7.4Hz. It was found that application of pressure decreased the secondary dendrite arms spacing (λ2) when compared with the no pressure experiments and cyclic pressure oscillations cause a resonance effect in the λ2 values when the pressure pulse frequency matches the arms’ natural frequency of formation. It is not yet clear if this resonance behavior is strong enough or reliable enough to be of potential interest for industrial applications seeking to employ novel approaches to controlling microstructural length scales during directional or equiaxed dendritic solidification processes.