Mechanism of fracture of dispersion-strenghthened tungsten

Conclusions In a dispersion-strengthened tungsten alloy fracture mechanisms change with rise in temperature in the same sequence as in unalloyed tungsten: quasibrittle cleavage at low temperatures is succeeded by partly tough fracture at 400°C (T_Br^u1), tough fracture through the body of the grain is observed in the range from 1000 (T_Br^u2) to 1600°C, and at 1800°C tough intergranular fracture commences. The cold-brittleness points of the dispersion-strengthened tungsten alloy are lower (T_Br^u1 by 100 and T_Br^u1 by 200°C) then those of unalloyed tungsten, while the temperature of transition to tough intergranular fracture is higher. As a result, the dispersion-strengthened alloy has a wider temperature range of tough transgranular fracture, with a larger value of. The wider range of tough transgranular fracture in the dispersion-strengthened tungsten alloy may be linked with a tendency for microvoids to form in the material on the second-phase particles, as a consequence of which subsequent fracture occurs by a microvoid coalescence mechanism.Translated from Poroshkovaya Metallurgiya, No. 7(283), pp. 31–35, July, 1986.