Embrittlement of sintered molybdenum predoped with carbon in high temperature oxygen-contaminated helium

Abstract

Changes in the tensile properties of sintered molybdenum sheets predoped with carbon which were exposed to impure helium for 100 h at 1000 °C were examined at low temperatures. Scanning electron microscopy was employed to determine the fracture modes of these specimens. Grain boundary segregations were measured using Auger electron spectroscopy. The following results were obtained. 1. (1) The ductility of the materials was substantially reduced after exposure to oxygen-contaminated helium. Concurrent oxygen contamination and decarburization are responsible for grain boundary weakening, particularly near the specimen surfaces. 2. (2) The addition of carbon before exposure was shown to reduce the embrittlement of the materials.