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 72 h. Mechanically alloyed powders were solid-state sintered at 1300degreesC for I h followed by secondary liquid-phase sintering at 1470degreesC for a sintering time ranging from 4 to 90 min. Liquid-phase sintering of oxide-dispersed tungsten heavy alloys at 1485degreesC for I h was also carried out. Oxide-dispersed tungsten heavy alloys containing 0.1-5 wt.% 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 800degreesC 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 10(4) s(-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. (C) 2003 Elsevier B.V. All rights reserved.