The Effects of Molybdenum Additions on the Sintering and Mechanical Behavior of Ultrafine-Grained Tungsten

Tungsten (W) is a brittle material at room temperature. Although the lack of ductility remains a difficult challenge, solid solution alloying of tungsten with rhenium offers an effective approach to improve tungsten’s room temperature brittleness. There are strong motivations to seek a substitute element for rhenium, because it is prohibitively expensive, for manufacturing solid solution tungsten alloys with improved mechanical behavior. As one of the potential substitute elements, the effects of molybdenum were studied in terms of its effects on densification and the grain growth of samples produced with nano-tungsten powder by pressureless sintering. A study on the mechanical properties of sintered tungsten-molybdenum alloy, including hardness, indentation toughness and bending stress–strain relationships, is also reported. It was found that alloying tungsten with molybdenum clearly reduced tungsten grain size, significantly increased hardness and indentation toughness, and also resulted in an appreciable improvement in tungsten’s tensile behavior during bending.