OSTWALD RIPENING IN LORENTZ-FORCE STABILIZED CU-PB DISPERSIONS AT LOW-VOLUME FRACTIONS .1. EXPERIMENTAL-OBSERVATIONS

We present measurements and theoretical investigations on Ostwald-ripe ning of Cu particles in a liquid Pb-Cu melt with low volume content of the phase dispersed. For this purpose we used a novel technique that is able to suppress sedimentation of particles in an electrically cond ucting matrix. The experiments on solid-liquid Cu-Pb dispersions in a low Volume fraction range, which is not accessible by conventional exp erimental techniques, reveal the existence of stationary particle size distributions. The particle growth differs significantly from the gro wth law of the LSW-theory for diffusion-controlled Ostwald ripening, i ndicating that in this system the particle coarsening is not only diff usion limited. We outline a new growth model based on the assumption o f preferred places for the trapping of Cu-atoms at dislocation sites e merging at the particle surface.