Dissolutive wetting in the Bi–Sn system

The isothermal dissolutive wetting behavior of various Bi–Sn alloys on pure Bi substrates was studied at 250 °C using the sessile drop technique. Wetted radius and apparent dynamic contact angle were recorded as a function of time. Sequential quenching and metallographic cross-sectioning were employed to investigate the temporal evolution of the S/L interface and the complete configuration of the contact line region. The macroscopic total contact angle was found to be close to 90° during spreading for the majority of Bi–Sn alloys investigated. The contact line mobility relationship, based on apparent dynamic contact angle, showed certain similarities to a universal correlation for partially wetting inert systems. Additional discussions of grain boundary effects and mass transport are presented.