A method was developed for the direct measurement of surface tension and surface free-energy using Udin's zero-creep technique at up to 1525K and at low oxygen partial pressures in hydrogen or in argon+hydrogen. The free surface energy at 1211K and at oxygen partial pressures, in a hydrogen atmosphere, of 5 x 10-16 to 5 x 10-18Pa was deduced to be 1520mJ/m2. Under the same conditions, a grain-boundary energy of 480mJ/m2 was deduced from shadow-graphs of grooves developed by the thermal etching of grain boundary/free-surface intersections.

Measurement of Free Surface Energy of Metals using the Zero Creep Method at Extremely Low Oxygen Partial Pressures. J.Fiala, O.Zverina, J.Cadek: Kovove Materialy, 1978, 16[1], 13-26