Supercooling during metal crystallization under conditions close to weightlessness using island vacuum condensates

Abstract

Island vacuum condensates the properties of which are determined by surface phenomena rather than the force of gravity actually permit to eliminate the effect of alien impurities and own oxides on supercooling ΔT during crystallization. Their application also allows to measure the dependence of ΔT on the contact angle θ between a droplet of a liquid metal and the substrate on which condensation and subsequent crystallization occur. For the metals under study (Au, In, Bi, Pb, Sn, Fe, Co, Ni) the supercooling ΔT is shown to increase with the angle θ growing. With wetting angles θ > 130 ° the supercooling ΔT does not depend anymore on the substrate material and for θ → 180° it approaches a value somewhat below 0.4 Ts, where Ts is the bulk melting temperature.