Phase Transformations of the Ti-40% Nb Alloy Under External Influence

Abstract

The phase transformations of the alloy Ti-40 mas % Nb after tempering and severe plastic deformation are studied. The phase transformations of the alloy according to the type and conditions of external influences are analyzed using methods of XRD, SEM and optical metallography. It is determined that inverse phase transformation of the metastable α''-phase to equilibrium β-phase is carried out after severe plastic deformation. Complete phase transformation α'' → β is typical for the mode, which consists of three pressing operation with the change of the loading axis in cramped conditions, followed by a multi-pass rolling in grooved rolls.

Development of Ultrafine–Grained and Nanostructured Bioinert Alloys Based on Titanium, Zirconium and Niobium and Their Microstructure, Mechanical and Biological Properties

“…The formation of such structures after quenching is typical for titanium-based alloys with a high niobium content of 30-45 wt %. [112,113]. The phase analysis based on the results of TEM SAED-patterns identification confirmed the presence of a β-solid solution of titanium and niobium, and a martensitic α -phase (Figure 14a,b, insert).…”

“…The phase content of the alloy changed after SPD, according to the XRD data (Figure 15b). As can be seen from the TEM data, after deformation, the metastable α -phase was transformed into a stable β-phase, according to the scheme α →→β + α [113]. Figure 16a,b illustrates the typical TEM images of the UFG Ti-45Nb alloy microstructure after three-cycle "abc"-pressing (e = 6.12) and MPGR (e = 2.01).…”