Composition Stability and Cr-Rich Phase Formation in W-Cr-Y and W-Cr-Ti Smart Alloys

W-Cr-Y smart alloys are potential material candidates for plasma facing components due to their protective behaviour during the loss-of-coolant accident (LOCA), while maintaining beneficial properties of W normal operation fusion power plant. During exposure, lighter alloying elements preferentially sputtered at surface, but in case a LOCA, quenches and sputtering stops diffusion surface becomes intensive. The Cr (Y, Ti) yields oxide layer stopping sublimation WO3. phase stability short-range ordering ternary W-Cr-Y(Ti) systems has been investigated, using combination Density Functional Theory (DFT) Cluster Expansion (CE) methods with Monte-Carlo (MC) simulations. It found out from DFT calculations, that all pairs system have positive values enthalpy mixing, most Cr-Ti Ti-W binary structures negative enthalpies mixing. shift order as function temperature between predicted result Y addition compared W70Cr30, by around 400 K towards lower temperatures. A strong tendency clustering observed even elevated temperatures (1800 K). decrease order–disorder transition (ODTT) observed, Ti not shown any significant changes W-Cr-Ti W-Cr alloy. Our MC simulations showed W70Cr29Y1 alloy mixing (Hmix) value is whole analysed range. Free energy above 1000 calculated first nearest neighbours approximation W70Cr29Ti1 alloys. results present investigations provide an insight enabling optimizing chemical composition materials future components.