High Temperature Mechanical Properties of Molybdenum Solid Solution Alloys

Demanding material requirements for space nuclear power systems have called for the use of refractory alloys. Molybdenum alloys are such candidate materials because of their good mechanical properties at fairly high temperatures, low neutron capture cross-section, and superior resistance to the attack of liquid metals. However, conventional Mo alloys have low ductility at lower temperatures. Hence, there have been several attempts to improve their viability. One of those approaches has been to alloy Mo with various alloying additions in solid solution, most notably with rhenium (Re). In this study the high temperature deformation behavior of various Mo-X (X Re, W, Nb, Hf) alloys is reviewed. High temperature deformation data for these solid solution alloys are analyzed in the light of existing deformation theories. Alloys with both Class-M and -A type behavior are identified and thus, various mechanisms are found to operate. Sometimes data interpretation becomes difficult due to the presence of second phase particles. Results are compared with unalloyed Mo to bring out the importance of solid solution alloying. (authors)