Intergranular fracture surface analysis of molybdenum

Abstract

Bend properties of plasma beam and/or electron beam melted molybdenum and several dilute alloys containing C, B, T, V and Re were investigated. Fracture surfaces and microstructure were examined in detail by SEM and AES.Considerable intergranular fracture occurred in almost all of the samples as the test temperature decreased. But proper alloy addition, such as B and Ti, and hot-rolling induced a change in the fracture mode to a transgranular mode. Segregation of nitrogen and/or oxygen to grain boundaries was often recognized in plasma beam or electron beam melted ingots and decreased the strength of grain boundaries. Small precipitates due to comparatively low alloy addition, such as C, B, Ti and Re, were effective to enhance the grain boundary cohesion.

Ab initiosearch for cohesion-enhancing impurity elements at grain boundaries in molybdenum and tungsten

“…For Mo, a study by Drachinskiy et al [7] showed that the segregation tendency to the GB is higher for O than for C. This is in accordance with Kumar and Eyre [3], for they stated that beneficial C removes the embrittling element O from the GB, but only for much higher C concentrations than O concentrations. Kadokura et al [8] observed a strong increase in GB cohesion when alloying with C and also Morito [9] found that C, as well as B, increases GB cohesion. Si in Mo was investigated by Sturm et al [10] concluding that Si lowers the GB cohesion and leads to preferred intergranular fracture.…”

Physical and Technological Aspects of Processing High-Purity Refractory Metals

“…The low technological plasticity and structural strength of refractory metals are particularly bad at medium and low temperatures. Studies [56][57][58] are shown that molybdenum of vacuum melting can be of the appreciable technological plasticity if the interstitials contents are lower than 1 × 10 -4 % of each element. These data for many years were a kind of a truth for researchers who worked on this problem.…”

Characteristics of EB-weldable molybdenum and Mo-Re alloys

“…25 It was found that PB melting refined and controlled impurities as well as EB melting. 26 Bend properties of PB-melted ingots and sheets were similar to those of EB alloys.…”