Tensile Flow Behaviour and Fracture Studies of Beta Titanium Alloys at Elevated Temperatures

Tensile testing on metastable beta alloy with various microstructures was carried out in this study. Beta 21S is a metastable alloy that exhibits a wide range of material characteristics depending on the processing techniques used. Three different sheets that have been used in this paper which has the same substance but three different microstructures. At a strain rate of 0.001/s, the tensile test was done on a single sheet at five different temperatures. The sheet has developed varied microstructures, the tensile nature of the material varies the alloy’s characteristics. Mechanical characteristics for 400°C, 500°C, 600°C, and 7000°C are described for 21S sheets. The alpha phase sheet elongated at room temperature by 1-3 %, whereas the pure beta phase sheet elongated by 22-24 %. There is a significant improvement in the extension of the sheet with the variation in temperature for the alpha phase. The elongation of the pure beta phase does not alter as the temperature rises. The fracture surface was tested at all temperatures and the optimal temperature for forming the sheet has been determined

Survey of Grain Boundary Energies in Tungsten and Beta-Titanium at High Temperature

Heat treatment is a necessary means to obtain desired properties for most of the materials. Thus, the grain boundary (GB) phenomena observed in experiments actually reflect the GB behaviors at relatively high temperature to some extent. In this work, 405 different GBs were systematically constructed for body-centered cubic (BCC) metals and the grain boundary energies (GBEs) of these GBs were calculated with molecular dynamics for W at 2400 K and β-Ti at 1300 K and by means of molecular statics for Mo and W at 0 K. It was found that high temperature may result in the GB complexion transitions for some GBs, such as the Σ11{332}{332} of W. Moreover, the relationships between GBEs and sin(θ) can be described by the functions of the same type for different GB sets having the same misorientation axis, where θ is the angle between the misorientation axis and the GB plane. Generally, the GBs tend to have lower GBE when sin(θ) is equal to 0. However, the GB sets with the <110> misorientation axis have the lowest GBE when sin(θ) is close to 1. Another discovery is that the local hexagonal-close packed α phase is more likely to form at the GBs with the lattice misorientations of 38.9°/<110>, 50.5°/<110>, 59.0°/<110> and 60.0°/<111> for β-Ti at 1300 K.

β-Ti Alloys for Orthopedic and Dental Applications: A Review of Progress on Improvement of Properties through Surface Modification

Ti and Ti alloys have charming comprehensive properties (high specific strength, strong corrosion resistance, and excellent biocompatibility) that make them the ideal choice in orthopedic and dental applications, especially in the particular fabrication of orthopedic and dental implants. However, these alloys present some shortcomings, specifically elastic modulus, wear, corrosion, and biological performance. Beta-titanium (β-Ti) alloys have been studied as low elastic modulus and low toxic or non-toxic elements. The present work summarizes the improvements of the properties systematically (elastic modulus, hardness, wear resistance, corrosion resistance, antibacterial property, and bone regeneration) for β-Ti alloys via surface modification to address these shortcomings. Additionally, the shortcomings and prospects of the present research are put forward. β-Ti alloys have potential regarding implants in biomedical fields.

Molecular dynamics investigation on tilt grain boundary energies of beta-titanium and tungsten at high temperature

The grain boundary energies (GBEs) of symmetric tilt grain boundaries (STGBs) and asymmetric tilt grain boundaries (ATGBs) for W at 0 and 2400 K and β-Ti at 1300 K were calculated by means of Molecular static method and Molecular dynamic simulations to investigate the effects of high temperature and grain boundary (GB) planes on the GBE. Generally, the variation trends of GBEs functioned with tilt angle are similar in the three cases when the tilt axis is specified. It is of course that these similarities result from their similar GB microstructures in most cases. However, the variation trends of β-Ti at 1300 K are somewhat different from that of W at 2400 K for STGBs with <100> and <110> tilt axes. This difference mainly stems from the following two reasons: firstly, the GB microstructures of W at 2400 K and β-Ti at 1300 K are different for some STGBs; secondly, the atoms at STGB of β-Ti at 1300 K tend to evolve into the local ω- or α-like structures distributed at STGBs, which make the corresponding STGBs more stable, thereby decreasing the GBEs. Furthermore, a geometric parameter θ, an angle between misorientation axis and GB plane, was defined to explore the effects of GB planes on GBEs. It was found that the relationship between GBEs and sin(θ) can be described by some simple functions of sin(θ) for the GBs with definite lattice misorientation, which can well explain and predict the preferred GB planes for the GBs with specific lattice misorientation. Our calculations not only extend the investigation of GBs to higher temperature, but also deepen the understanding on the temperature contribution to the microstructure evolution at GBs and on the relationship between GBE and possible geometric parameters.

Vertical and Orovestibular Forces Generated by Beta-Titanium and Stainless-Steel Rectangular Wires in Labial and Fully Customized Lingual Bracket Systems

This study aimed to investigate the force values exerted from rectangular wires when combined with conventional labial and fully customized lingual appliances under predefined, idealized activation. Fully customized lingual brackets of two brands Incognito™ (3M Unitek, Monrovia, MN, USA) and WIN (DW Lingual Systems, Bad Essen, Germany) and labial brackets of another brand, discovery® MIM and discovery® smart systems (Dentaurum, Ispringen, Germany), were chosen. Stainless-steel and beta-titanium wires of 0.018” × 0.025” were examined. For IncognitoTM, 0.0182” × 0.025” beta-titanium wires were tested. Intrusion/extrusion and orovestibular movements were performed in a range of 0.2 mm, and the forces were recorded for each 0.1 mm of the movement. Mean values and standard deviations were calculated for all measurements, and ANOVA was performed for statistical analysis. Slight differences were observed between the forces generated from beta-titanium and stainless-steel wires. The same wire generated in some cases 5–53% higher forces with the lingual appliance due to the vertical orientation of the long walls during intrusion/extrusion and increased wire stiffness at the anterior region. Beta-titanium and stainless-steel 0.018” × 0.025” wires can generate similar force values during the final stages of the orthodontic therapy; thus, possibly only one of the two alloys could be used in each orthodontic wire sequence.

Electrochemical and biological behaviour of near β Titanium alloy for biomedical implant applications

Pulsed laser deposition technique (PLD) is one of the methods to coat hydroxyapatite on near beta titanium alloys (Ti-13Nb-13Zr) implants which are used in orthopaedics and dentistry applications. In this study, Hydroxyapatite (HA) ceramics in the form of calcium phosphate (Cap) were deposited on nearβ Titanium alloys (Ti-13Nb-13Zr) by the pulsed laser deposition method. The coated thin film was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) with Energy dispersive spectroscopy (EDS) and atomic microscopy (AFM). The corrosion studies were carried out coated and uncoated samples using potentiodynamic polarisation studies in simulated body fluid (Hanks’ solution). The bioactivity of the Hap-coated samples on nearβ Titanium alloys was evaluated by immersing them in simulated body fluid (SBF) for nine days. XRD and EDS analysis confirmed the presence of hydroxyapatite. The corrosion studies showed that the treated samples have better corrosion resistance compared to uncoated substrates. The formation of apatite on treated samples revealed the bioactivity of the Hap-coated substrates. HA-coated nearβ Titanium alloys provide higher corrosion protection than substrates, which can be used for biomedical implant applications.