Tungsten alloys are candidate materials for DEMO divertor applications because of their high melting point and low sputtering yield. We explore, using ab initio methods, the phase stability trend of W-Ta and W-V alloys. The available experimental phase diagrams of these alloys describe phase stability only in the high temperature limit. In this study, structural and phase stability, point defects and anisotropic elasticity properties of binary W-Ta and W-V alloys are investigated as functions of alloy composition, through a combined density functional theory and Monte-Carlo approach. For W-Ta alloys we find that for the more stable phases the order-disorder transition temperature is close to 600 K. This is coherent with recent mechanical test, which show that the ductile-to-brittle transition temperatures of all the W-V and W-Ta alloys are higher than that of pure W. Crown Copyright (C) 2012 Published by Elsevier B. V. All rights reserved.