SURFACE PHASES IN BINARY-LIQUID METAL-ALLOYS - AN X-RAY STUDY

Surface-sensitive x-ray scattering techniques with atomic scale resolu tion are employed to investigate the microscopic structure of the surf ace of three classes of liquid binary alloys: (i) Surface segregation in partly miscible binary alloys as predicted by the Gibbs adsorption rule is investigated for Ga-In. The first layer consists of a supercoo led In monolayer and the bulk composition is reached after about two a tomic diameters. (ii) The Ga-Bi system displays a wetting transition a t a characteristic temperature T(w)approximate to 220 degrees C. The t ransition from a Pi monolayer on Ga below T-w to a thick Pi-rich wetti ng film above T-w is studied. (iii) The effect of attractive interacti ons between the two components of a binary alloy on the surface struct ure is investigated for two Hg-Au alloys.