For a significant increase in operating temperatures in energy conversion processes, alternative constituent phases for new high-temperature alloys beyond tradition Ni-basis superalloys have to be explored. Candidate materials that come to mind because of their high melting points are refractory metals such as V, Cr, Nb, Mo, Ta or W. But refractory elements typically show low fracture toughness and ductility at low temperature and endanger the structural integrity of, for example, turbines. In fact, body centred cubic metals typically show a ductile-brittle transition at a certain temperature, which can be extremely sensitive to small variation of impurity levels and alloying elements.
Using atomistic simulations on high performance computer, the role of impurities and alloy composition on the dislocation nucleation and migration is investigated to extract and compare their experimental signatures on the deformation behaviour associated with dislocation-induced brittleness. The goal is to develop a simulations-informed predictive model on dislocation-mediated ductility/brittleness.