Despite exhibiting the highest melting point of all metals, the technological use of tungsten is hampered by its room-temperature brittleness. Alloying with Re significantly ductilizes the material which has been assigned to modified properties of the $1/2⟨111⟩$ screw dislocation. Using density functional theory, we show that alloying induces a transition from a symmetric to an asymmetric core and a reduction in Peierls stress. This combination ductilizes the alloy as the number of available slip planes is increased and the critical stress needed to start plastic deformation is lowered.

• Received 7 June 2009

DOI:https://doi.org/10.1103/PhysRevLett.104.195503