Microstructure evolution of nanostructured β-Ti-25at% Nb alloy produced by high-pressure torsion from elemental powders

β-Ti alloys are of special interest in the medical industry due to their suitable elastic modulus for bone implant applications. In this study, a Ti-25at%Nb alloy was sintered from elemental powders using high-pressure torsion (HPT) under 6 GPa. Disk samples subjected to 30, 50, and 100 revolutions at 1 rpm were prepared for microstructural analysis, especially the evolution of grain refinement and β-phase formation. X-ray diffraction (XRD) shows signals corresponding to the β-Ti become more prominent with increasing number of revolutions, while scanning electron microscopy (SEM) revealed that the homogeneity of elemental mixing is higher at the edge of the disks. Correlation of Vickers microhardness to grain size observation by transmission electron microscopy (TEM) reveals that microhardness increases proportionally to the strain imposed by HPT but slightly decreases and saturates when microstructure shows a more homogeneous distribution of nanostructured β-phase grains, retaining only a small fraction of α-Ti phase. Graphical abstract: [Figure not available: see fulltext.]