An Improvement in the Ductility of Beryllium at High Temperatures

Abstract

THE outstanding problem in beryllium metallurgy is the lack of ductility exhibited by the metal, both at room temperature and at elevated temperatures. At room temperature, brittleness can be attributed to the ease of cleavage of basal planes of the hexagonal lattice, and to the high yield-strength of the prismatic planes, while at temperatures above 400° C., intergranular failure predominates. A ductility maximum occurs at intermediate temperatures depending on the strain-rate used, tensile specimens failing with a ductile, fibrous fracture between 200° and 400° C. These fracture modes overlap, and two or more types of failure may be seen in any one tensile specimen.