Ductility and precipitation in sintered tungsten alloys

The effects of post-sintering heat treatments were studied employing two tungsten alloys. For the first alloy, a typical heavy alloy with 90 wt.% W, heat treatments (T > 600 °C) resulted in improved tensile ductility. For the second alloy, the composition of which was similar to that of the matrix phase of a heavy alloy, heat treatments resulted in age hardening as a result of precipitation phenomena, none of which were observed in the matrix of heavy alloys. It was thus concluded that the improved ductility of heat-treated heavy alloys is not caused by precipitation but rather is due to other factors, such as residual interfacial thermal stress relief together with dissolution of embrittling phases and/or elements.