Non-equilibrium stabilization of a ductile disordered phase in a high-aluminum refractory alloy

Abstract High-aluminum refractory compositionally complex alloys are intrinsically brittle due to ordering and grain-boundary intermetallics. We show that extreme thermal gradients during selective laser melting kinetically suppress these transformations in NbMoCrTiAl, stabilizing a disordered A2 solid solution despite strong thermodynamic driving forces for B2 ordering and C14/A15 formation. Multi-scale characterization and kinetic simulations reveal how rapid liquid-solid and solid-state transformations dissolve intermetallic phases and prevent reordering during cooling. The resulting precipitate-free A2 microstructure exhibits substantially enhanced room-temperature plasticity, overcoming brittleness without compositional modification. Our results establish non-equilibrium processing as a route to access otherwise inaccessible phase states in refractory complex alloys, expanding the design space of high-temperature structural materials.