Fabrication and properties of mechanically alloyed oxide-dispersed tungsten heavy alloys

The microstructures and mechanical properties of mechanically alloyed oxide-dispersed tungsten heavy alloys were investigated. Elemental powders of tungsten, nickel, and iron of a composition corresponding to 93W–5.6Ni–1.4Fe (wt.%) were mechanically alloyed with additional Y2O3 powders in a tumbler ball mill for 72h. Mechanically alloyed powders were solid-state sintered at 1300°C for 1h followed by secondary liquid-phase sintering at 1470°C for a sintering time ranging from 4 to 90min. Liquid-phase sintering of oxide-dispersed tungsten heavy alloys at 1485°C for 1h was also carried out. Oxide-dispersed tungsten heavy alloys containing 0.1–5wt.% Y2O3 can be obtained and oxide dispersoids effectively inhibit the coarsening of tungsten particles during sintering. A high temperature compression test of tungsten heavy alloys at 800°C showed that the strength of mechanically alloyed oxide-dispersed tungsten heavy alloys increased with the oxide content. In split-Hopkinson bar tests at a strain rate of 104s−1, the oxide-dispersed tungsten heavy alloy showed a tendency for premature failure during localized shear deformation due to debonding at the oxide/matrix interfaces.