The surface tension of liquid aluminium in high vacuum: The role of surface condition

Despite the fact that aluminium is one of the most widely used metals, there is still a great uncertainty, of the order of 25%, on the intrinsic value of its surface tension σ. The origin of this large dispersion, which is much higher than the typical error of σ measurements (2–3%), is undoubtedly the high sensitivity of surface properties of molten Al to oxygen. In the present study the question of the surface tension of pure Al and its relationship to the surface condition is discussed in the light of new surface tension results obtained by employing an accurate technique (the “large drop” technique) that minimizes the experimental error on σ, and high vacuum/high temperatures to promote deoxidation of molten Al.