Nucleation kinetics studies on embedded nanosized indium (In) particles

Abstract

Indium exhibits a monotectic reaction with Al at an invariant temperature (910 K) and composition (4.7 at.% In). Ultra rapid cooling, using gun technique, of monotectic compositioned alloy led to a microstructure in which In was distributed uniformly with a bimodal size distribution. Quantitative metallographic analysis revealed size of small sized In particles to be in the range of 10-20 nm whereas bigger particles were found to be even greater than 200 nm in size. These particles of In undercooled by 19 K in the rapidly solidified product of Al-In system. In the as-cast condition the degree of undercooling was only 9 K. Analyses of the nucleation rate measurements showed that the activation energy barrier to nucleation is 2.666 kcal/mol at undercoolings approaching 19 K. The nucleus-substrate contact angle was found to be 20°, which signifies that Al provides a potent catalytic surface for the nucleation of In.