Tungsten (W) is a refractory body-centered-cubic (bcc) metal with exceptional high-temperature strength and an extremely high melting point. However, its ductile-to-brittle transition temperature (DBTT) occurs above room temperature, significantly restricting its formability and, consequently, its range of applications. One approach to modifying the plastic behavior of W at low temperatures is alloying it with rhenium (Re), which enhances its ductility, though the underlying dislocation mechanisms responsible for this improvement are not fully understood. In this work, the phase field dislocation dynamics model is extended to treat {112}$\langle 111\rangle$ dislocation dynamics in a bcc crystal and applied to elucidate the effect of Re additions on dislocation mechanisms in W. The model is used to simulate thermally activated glide of long, initially screw and edge dislocations in W and W-20%Re for a range of elevated temperatures that includes their DBTT. We show that for both materials and at all temperatures, the critical resolved shear stress (CRSS) for {112} glide is higher than for {110} glide and the CRSS for screw dislocations is higher than edge dislocations. The CRSS is higher in the {112} antitwinning (AT) direction than {112} twinning (T) direction up to a certain temperature, at which they become nearly equal. The {112}T/AT equivalence temperature is lower for W-20Re than pure W. We find that Re increases the activation enthalpy for screw dislocation glide for the {110} mode, but decreases it for the {112} mode. Together, these findings suggest that Re additions promote slip activity from being primarily {110} slip to both {110} and {112}T/AT slip.

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• Line defects
• Mechanical deformation
• Alloys
• Metals
• Molecular dynamics
• Phase-field modeling
• Time-dependent Ginzburg-Landau theory