Tensile Behavior of Nb7.5Ta for Heat-Exchanger Applications

Hydrogen generation using sulfur-iodine cycle involves the formation and decomposition of sulfuric acid and hydrogen iodide (HI). The decomposition of HI has been proposed to occur at a maximum temperature of 400°C. Nb7.5Ta has been identified as a candidate structural material for use in heat-exchanger during the decomposition of HI. This paper presents the results of tensile testing at temperatures ranging from ambient to 400°C. A gradual drop in tensile strength was noted with increasing temperature. Reduced failure strain was observed at temperatures up to 300°C, which is known to be associated with the occurrence of dynamic strain aging (DSA). Since the concentration of precipitate and dislocations can influence the DSA behavior of susceptible materials, efforts are in progress to characterize dislocations using transmission electron microscopy. All tested specimens exhibited ductile failures, characterized by dimples