THE SURFACE OF LIQUID DILUTE METAL-ALLOYS IN VACUUM

The authors report work-function measurements and Auger spectroscopy of liquid gallium-aluminium alloys which indicate that the surfaces of liquid dilute alloys can have an instability in vacuum less than ultra-high that is quite distinct from normal surface oxidation. The solute (aluminium) continuously diffuses to the surface where it oxidises to form an insoluble oxide. Even in very dilute liquid alloys the surface eventually becomes covered in a layer of the oxidised solute, so the surface properties are unlike those of either the solute metal or its oxide. This may explain some anomalies that have been obtained in the surface properties of liquid alloys.