FLOW-STRESS OF PURE NIOBIUM BETWEEN 2200 K AND THE MELTING-POINT 2741 K

The creep tests reported in the literature have been performed at temperatures up to about 2200 K. Conventional equipment for creep tests at temperatures above 2300 K has been used for short time tests only. This letter reports on first results obtained by a newly developed method. The tests were performed in ultra high vacuum and made use of the centrifugal forces acting on a spherical sample rotating freely in an electromagnetic levitation field. Among the advantages are the smallness of the specimen and the absence of loading grips.