Synthesis of high-strength W-Ta ultrafine-grain composites

摘要

Bulk samples of an ultrafine-grained tungsten-tantalum composite alloy have been synthesized by consolidating mechanically milled composite powders. The grain growth during densification is limited due to the submicron-scale layering of the individual metals in the composite particles and the relatively low sintering temperature (1300 ℃). The ultrafine microstructure of the high-density (～99% theoretical density) samples leads to a high yield stress of ～3 GPa under quasi-static uniaxial compression. A tendency for Ta-rich solid-solution formation during densification was observed, and the high-temperature phase equilibria in the composite powders were examined further using high-energy x-ray diffraction at temperatures up to 1300 ℃.