Enhancing thermal stability of Nb nanowires in a NiTiFe matrix via texture engineering

Metallic nanowires, renowned for their high strength and large elastic strain limits, have shown significant potential in rendering extraordinary structural and functional properties in composites. However, their integrity at high temperatures is often compromised due to fragmentation and spheroidization, processes driven by excess interfacial energy. Here, we demonstrate in a NiTiFe/Nb nanocomposite that the fragmentation and spheroidization of Nb nanowires can be significantly suppressed by tailoring the interfacial crystallographic orientation relationship between the nanowires and the matrix. By doping Fe into NiTi, we inhibit the typical deformation-induced amorphization of the NiTi-based matrix during severe deformation processing. The common (111)_NiTi//(110)_Nb texture is inherently suppressed and (110)_NiTiFe//(110)_Nb texture is formed instead. Such a change in texture allows Nb nanowires to retain their integrity up to 700 °C in the NiTiFe matrix, in contrast to the 550 °C in the counterparts. Simulation results indicate that the enhanced thermal stability of Nb nanowires is attributed to the reduced interfacial energy between (110)_NiTiFe and (110)_Nb. Additionally, Fe doping elevates the migration energy barrier for Nb diffusion, imposing further resistance to fragmentation and spheroidization. © 2024 Acta Materialia Inc.