In-situ investigation of stress-induced martensitic transformation in Ti–Nb binary alloys with low Young's modulus

Abstract

Microstructure evolution, mechanical behaviors of cold rolled Ti-Nb alloys with different Nb contents subjected to different heat treatments were investigated. Optical microstructure and phase compositions of Ti-Nb alloys were characterized using optical microscopy and X-ray diffractometre, while mechanical behaviors of Ti-Nb alloys were examined by using tension tests. Stress-induced martensitic transformation in a Ti-30at.%Nb binary alloy was in-situ explored by synchrotron-based high-energy X-ray diffraction (HE-XRD). The results obtained suggested that mechanical behavior of Ti-Nb alloys, especially Young's modulus was directly dependent on chemical compositions and heat treatment process. According to the results of HE-XRD, α＂-V1 martensite generated prior to the formation of α＂-V2 during loading and a partial reversible transformation from α＂-V1 to β phase was detected while α＂-V2 tranformed to β completely during unloading.

Microstructure and nanomechanical properties of magnetron sputtered Ti − Nb films

“…In fact, for 15 at.% Nb content, the hcp pure titanium is converted to an orthorhombic structure which is characterized by martensitic ′′ − Ti. The this martensitic phase at Nb concentrations around 15 at.% is supported by several other publications[47,48]. Furthermore, at 20 at.% of Nb content and beyond, the − Ti phase (bcc) can be stabilized at room temperature.…”

“…At 15 at. % Nb, the orthorhombic martensite ′′ − Ti is formed with the lattice constants = 3.047, = 4.929, = 4.688 in close agreement with database values = 3.100, = 4.880, = 4.700[47,48]. The broad…”

Crystal Structure Evolution, Microstructure Formation, and Properties of Mechanically Alloyed Ultrafine-Grained Ti-Zr-Nb Alloys at 36≤Ti≤70 (at. %)

“…The biocompatibility of niobium was also concerned to be higher than titanium [10]. Ti-Zr [11][12][13][14][15] and Ti-Nb systems [16][17][18][19][20][21] were already examined in several articles. It was reported that Ti-Zr alloys can improve biocompatibility properties of pure titanium, their mechanical strength and grind ability [13,14].…”

The dynamic response of β titanium alloys to high strain rates at room and elevated temperatures

“…The thermal part is controlled by shot-range barriers such as the intersection of dislocations and the Peierls stress which is sensitive to temperature and strain rate. A higher strain rate can accelerate the multiplicity of dislocations, leading to the formation of dislocation tangles [53][54][55] which will retard the movement of dislocations. In addition, a higher temperature will supply dislocations with sufficient thermal energy to help them overcome dislocation tangles [33,41].…”

“…The origin of low Young's modulus in Ti-Nb-Ta-Zr alloys [51] and cold worked Ti-Nb-Ta-Zr-O alloys [52] have been studied and it is reported that "Young's modulus is lowest near the Martensite start temperature (M s )". Chang et al [53] investigated the effect of microstructures on the Young's modulus for Ti-Nb based alloys with different Nb contents and concluded that the Young's modulus depends directly on the chemical compositions of the alloy and its heat treatments.…”