Search

W alloys are currently widely studied materials for their potential application in future fusion reactors. In the presented study, we report on the preparation and properties of mechanically alloyed W-Ti powders compacted by pulsed electric current sintering. Four different powder compositions of W-(3%-7%)Ti with Hf or HfC were prepared. The alloys' structure contains only high-melting-point phases, namely the W-Ti matrix, complex carbide (Ti,W,Hf)C and HfO2 particle dispersion; Ti in the form of a separate phase is not present. The bending strength of the alloys depends on the amount of Ti added. The addition of 3 wt. % Ti led to an increase whereas 7 wt. % Ti led to a major decrease in strength when compared to unalloyed tungsten sintered at similar conditions. The addition of Ti significantly lowered the room-temperature thermal conductivity of all prepared materials. However, unlike pure tungsten, the conductivity of the prepared alloys increased with the temperature. Thus, the thermal conductivity of the alloys at 1300 °C approached the value of the unalloyed tungsten. [ABSTRACT FROM AUTHOR]

Tungsten alloys currently represent prospective candidates to replace tungsten in the first wall applications in future fusion facilities. Tungsten has many advantageous features; however, it is rather susceptible to oxidation at temperatures above around 500 °C. To mitigate/suppress this, various oxide-forming elements are being added to tungsten to induce self-passivation. The most common ones are chromium, titanium and silicon. The alloyed powder is frequently prepared by mechanical alloying and then consolidated by a sintering method. Most of the published results are related to alloys consolidated by HIP process that leads to formation of multiphase material. In the presented study, W-10Cr alloy with hafnium oxide particle dispersion was prepared by spark plasma sintering. Unique features of the microstructure are discussed and compared with other processing methods Phase and thermal stability of the alloy was evaluated at three fusion-relevant temperatures using detailed X-ray diffraction analysis, differential thermal analysis and microstructural observations in a scanning electron microscope. Impact of the heat treatment on crucial properties such as thermal conductivity and heat capacity was evaluated. [ABSTRACT FROM AUTHOR]