CHARACTERISTICS OF EB-WELDABLE MOLYBDENUM AND MO-RE ALLOYS

The electron-beam weldability, structure, and mechanical behavior of molybdenum and Mo-Re alloys produced via powder metallurgy were characterized by comparison with those produced by ingot metallurgy. By establishing the fabrication and processing for reducing the total oxygen of the starting materials, sound electron-beam welds of the powder metallurgy materials could be obtained. Intergranular embrittlement in the weld metal was improved by heat treatment. Carbon doping and postweld heat treatment were significantly effective to recover the strength and, therefore, the ductility. This is primarily attributed to an increase of the grain boundary cohesion due to the effective carbon segregation and precipitation. As a result, it was found that the welds of the powder metallurgy materials have good potential not only for high-performance materials but also for structural components.