Modelling of nodular particle growth in a liquid-solid film during condensation experiments of copper-silver alloys

Abstract

Silver-copper alloys are condensed in a liquid-solid domain of the phase diagram on a tilted molybdenum substrate regulated in temperature. After a droplets regime, a film which contains a monolayer of nodular solid crystals forms. The size distribution and density of the particles in the film are measured after different condensation times. Results show that in our experimental conditions a ripening process occurs which is evidenced by a decrease of the number of particles with time, and a broad particle size distribution. However, the decrease rate is smaller than expected without a condensation flux. A model is then developed to interpret and generalize these results. This model results from the modification of the Lifshitz-Slyosov model [1] to take into account the supply from the vapour phase. It is shown that the higher the flux of material to solidify from the vapour phase is, the more the growth from the vapour phase overcomes the ripening process. Once the particle density reaches a characteristic value which is simply proportional to the incoming flux, no more particles are dissolved. The system then tends towards a monomodal distribution with a radius which grows in t 1/3 .