Interstitial-Driven Phase Evolution and Deformation in Nb-Based Refractory Alloys
Ravit Silverstein, Florent Mignerot, Nicoló Maria della Ventura, Julia Pürstl, Tresa M. Pollock and Daniel S. Gianola
BCC based refractory multi-principal element alloys (RMPEAs) are promising materials for high-temperature application due to their high melting points and high strength retention. To balance strength, ductility, and oxidation resistance, there is a growing interest in multi-phase alloys rather than single-phase solid solutions. Recently, an increasing number of studies have shown that the incorporation of a dilute amount of interstitials into RMPEAs can lead to high strength levels. However, the full implications of competing phase transformations, microstructural evolution, and their effects on dislocation interactions remain unclear. To unpack this behavior, this study delves into interstitial effects on phase evolution and mechanical behavior of BCC Nb–Ti alloys as a model system for understanding these phenomena in more complex, multi-component systems. This study reveals that incorporating interstitials in dilute concentrations into Nb-Ti alloys can effectively promote nanoscale architectures that promote elevated strength levels (up to 3 GPa in tension) and break the typical strength-toughness dichotomy. Our findings highlight the formation of intermediate structures along the Burgers path and establish their correlation with strengthening models based on the structural wavelengths, providing valuable insights for designing high-performance refractory alloys.