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High Entropy Alloys
Published in T.S. Srivatsan, Manoj Gupta, High Entropy Alloys, 2020
P. Neelima, S.V.S. Narayana Murthy, P. Chakravarthy, T.S. Srivatsan
The mechanical properties of titanium alloys at both room temperature (27°C) and elevated temperature for the alpha/near-alpha, alpha + beta, and beta alloys [57] are summarized in Table 15.15. These alloys have high specific strength (σ/ρ) and are often chosen for use in aerospace-related applications. Controlled processing of these alloys is essential to obtain both the desired microstructure and repeatable properties. The mechanical properties of commercial refractory alloys [58], namely niobium (Nb), molybdenum (Mo), tantalum (Ta), and tungsten (W) at elevated temperatures are summarized in Table 15.16. Some of these alloys are used for very high-temperature applications. However, oxidation is a problem at high temperatures and a suitable coating (like the silicide coating on a niobium alloy C-103) is often given to overcome the problem.
Nuclear Fission Reactor
Published in C. K. Gupta, Materials in Nuclear Energy Applications, 1989
The RBMK is fueled with enriched UO2 (2%) clad in a zirconium alloy and cooled by light water which is allowed to boil. Fuel burn-up averages 20,000 MWd/t and the reactor can be refueled on load. Pressure, outlet temperature, and thermal efficiency are similar to other boiling-water reactors. There is, however, nothing like the RMBK anywhere in the western world in civil nuclear power. The moderator is a cylindrical stack of graphite blocks pierced by more than 1500 vertical fuel channels consisting of zirconium-niobium alloy pressure tubes to cool both the fuel and the graphite. The moderator operates at a peak temperature of around 700°C, or around 350°C at the pressure tubes. To prevent oxidation of the graphite, the moderator is enclosed in a thin steel vessel in which an inert atmosphere of helium and nitrogen is maintained. A simplified schematic of this reactor system is shown in Figure 25.
Magnetic Separation
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2022
James H. P. Watson, Peter A. Beharrell
This has been demonstrated in practice since the mid-1980s when Eriez Magnetics of Pennsylvania, USA built the first superconducting coiled magnetic separator for use in the kaolin industry (Figure H1.13.4). This system had a moderate processing capacity and ran at an operating field of 1 T generated by a niobium alloy superconducting coil cooled by reliquefied helium [1].
Additive manufacturing of bimetallic structures
Published in Virtual and Physical Prototyping, 2022
Amit Bandyopadhyay, Yanning Zhang, Bonny Onuike
Figure 6 shows different bimetallic structures processed via direct joining by conventional and AM methods. For conventional processes, Figure 6(a,b) show bimetallic structures of titanium alloy/stainless steel materials fabricated via laser butt welding and diffusion bonding processes, respectively (Chen et al. 2014; Kundu, Sam, and Chatterjee 2011). These joints showed critical bonding issues due to titanium and stainless steel incompatibility. However, niobium alloy (C103)/nimonic alloy (C263) joint produced through explosive cladding technique (Mastanaiah et al. 2014) showed good bonding at the interface Figure 6c. The direct deposition approach has been widely used through AM processes to fabricate bimetallic joints of compatible dissimilar metals. For instance, GRCop-84 was directly deposited on Inconel 718 material via the LENS process (Onuike, Heer, and Bandyopadhyay 2018), Figure 6d. The base materials are metallurgically compatible since Ni-Cu, the base alloy’s main constituent element, is an isomorphous alloy system that exhibits complete solubility. The Inconel 718/GRCop-84 bimetallic structure showed good interfacial bond strength. However, an alloy system like Al-Cu that exhibits complex binary phases coupled with the base materials’ low laser absorptivity is challenging to process into the bimetallic joint using the laser metal deposition (LMD) methods. Although Zhang et al. (Zhang, Gong, and Liu 2015) investigated the feasibility of fabricating such joint using the friction stir welding method, the bond strength was low, as shown in Figure 6e.
Assessment of stress/strain in dental implants and abutments of alternative materials compared to conventional titanium alloy—3D non-linear finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Pedro Henrique Wentz Tretto, Mateus Bertolini Fernandes dos Santos, Aloisio Oro Spazzin, Gabriel Kalil Rocha Pereira, Atais Bacchi
Among those alternatives, the titanium-zirconia alloy presented success rates and peri-implant bone resorption similar to titanium (Iegami et al. 2017) with the advantage of presenting a slightly lower modulus of elasticity (100 GPa) (Akça et al. 2015). Still, the titanium-niobium alloy with 70% porosity, known as ‘porous titanium’, reached an elastic modulus much closer to that of the bone (∼60 GPa), good biocompatibility, greater bone growth, and demonstrated superior corrosion resistance in comparison to pure titanium (Xu et al. 2013). Another clinical standpoint to be considered is that titanium implants also present the potential for discoloration of peri-implant gingival tissue and possible hypersensitivity (Schwitalla and Müller 2013), thus, metal-free alternatives to titanium were investigated. Ceramics, more specifically tetragonal zirconia stabilized with yttrium, a polycrystalline ceramic, has shown to have a high survival rate and little marginal bone loss, comparable to those found with titanium implants (Deeksha et al. 2012; Pieralli et al. 2017). There are no reports of substantial accumulation of bacteria around this material (Deeksha et al. 2012). As for the mechanical properties, it has sufficient fracture strength to withstand the masticatory loads. In addition to the biological and mechanical points, zirconia becomes an aesthetic alternative to titanium implants (Deeksha et al. 2012).
Ectoine hydration, aggregation and influence on water structure
Published in Molecular Physics, 2019
Michael Di Gioacchino, Fabio Bruni, Armida Sodo, Silvia Imberti, Maria Antonietta Ricci
NDIS is a powerful method for the investigation of molecular hydration and hydrogen bonding interaction in aqueous solutions, as neutrons are strongly scattered by hydrogens and can distinguish between isotopes [34]. This property allows recording richer information in comparison with X-ray diffraction experiments, thus providing better constraints to the EPSR fitting procedure (described in the following). The experiment has been performed at the ISIS spallation source (STFC, UK), on the SANDALS diffractometer [35], at ambient conditions (298 K), using standard Ti–Zr sample containers (1 mm thickness). Each sample, listed in Table 1, has been exposed to the neutron beam between 12 and 14 h corresponding to a total proton current at the ISIS target of 1500–1750 µA. Data have also been collected for empty containers, empty instrument and vanadium–niobium alloy standard. These data allow to obtain the total interference differential scattering cross-section, , shown in Figure 2, after correction for systematic errors and normalisation via the GUDRUN routine [36].