Abstract
The effect of heat-treatment in vacuo and hydrogen on ductility and UTS of the sintered 95.5 W-3.0 Ni-1.5 Fe and 91.3 W-5.8 Ni-2.9 Fe (by wt%) heavy alloys has been studied. The influence of composition and microstructure upon the mechanical properties of the cold worked (swaging) alloys is also presented in this paper.
These materials were heated at 400-1200°C in hydrogen atmosphere and in vacuo, and the mechanical properties of heat treated alloys were tested.
The effect of vacuum treatment was attributed to the removal of hydrogen embrittlement, and values of UTS and elongation increased after the vacuum treatment.
The scanning electron micrographs of the fracture surfaces showed that hydrogen weakens mainly the interface between tungsten-matrix phase boundaries, and W-grain boundaries.
High ductility was found to be connected to a high binding strength between the tungsten grains and the matrix phase.
