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Shape Memory Alloys (SMAs) can play an essential role in developing novel active sensors for self-healing, including aeronautical systems. However, the NiTi SMAs available in the market are almost limited to wires, small sheets, and coatings. This restriction is mainly due to the difficulty in processing NiTi through conventional processes. Thus, the objective of this study is to evaluate the potential of one of the most promising routes for NiTi additive manufacturing—material extrusion (MEX). Optimizing the different steps during processing is mandatory to avoid brittle secondary phases formation, such as Ni3Ti. The prime NiTi powder is prealloyed, but it also contains NiTi2 and Ni as secondary phases. The present study highlights the role of Ni and NiTi2, with the later having a melting temperature (Tm = 984 °C) lower than the NiTi sintering temperature, thus allowing a welcome liquid phase sintering (LPS). Nevertheless, the reaction of the liquid phase with the Ni phase could contribute to the formation of brittle intermetallic compounds, particularly around NiTi and NiTi2 phases, affecting the final structural properties of the 3D object. The addition of TiH2 to the virgin prealloyed NiTi powder was also studied and revealed the non-formation of Ni3Ti for a specific composition. The balancing addition of extra Ni revealed priority in the Ni3Ti appearance, emphasizing the role of Ni. Feedstocks extruded (filaments) and green strands (layers), before and after debinding & sintering, were used as homothetic of 3D objects for evaluation of defects (microtomography), microstructures, and mechanical properties. The composition of prealloyed powder with 5 wt.% TiH2 addition after sintering showed a homogeneous matrix with the NiTi2 second phase uniformly dispersed.

The investigations on estimating the attenuation of capture gamma radiation by a composite neutron-shielding material based on modified titanium hydride and Portland cement with a varied amount of boron carbide are performed. The results of calculations demonstrate that an introduction of boron into this material enables significantly decreasing the thermal neutron flux density and hence the levels of capture gamma radiation. In particular, after introducing 1- 5 wt.% boron carbide into the material, the thermal neutron flux density on a 10 cm-thick layer is reduced by 11 to 176 factors, and the capture gamma dose rate – from 4 to 9 times, respectively. The difference in the degree of reduction in these functionals is attributed to the presence of capture gamma radiation in the epithermal region of the neutron spectrum.

Atom probe tomography (APT) has been increasingly used to investigate hydrogen embrittlement in metals due to its unique capacity for direct imaging of H atoms interacting with microstructural features. The quantitativeness of hydrogen measurements by APT is yet to be established in views of erroneous compositional measurements of bulk hydrides and the influence of spurious hydrogen, e.g. residual gas inside the analysis chamber. Here, we analyzed titanium deuteride (approx. 65.0 at%-66.6 at% D) in lieu of hydride to minimize the overlap with residual gas, both with laser pulsing and high-voltage (HV) pulsing. Strategies were deployed to prevent H pick-up during specimen fabrication, including preparing specimens at cryogenic temperature. The measured composition of deuterium by APT with laser pulsing decreases significantly with the applied laser pulse energy, which is interpreted with regards to the strength of the corresponding surface electrostatic field, as assessed by the evolution of charge-state ratio. In contrast, compositional analyses with HV pulsing are roughly independent of the applied experimental parameters, although approx. 15 at%-20 at% off the nominal composition. Aided by plotting paired mass-to-charge correlations, the mechanisms of composition bias in both pulsing modes are discussed. A special emphasis is placed on the local variations of the measured composition as a function of the local electric field across the specimen's surface, which is not uniform due to asymmetric heat distribution related to the localized laser absorption and the faceted nature of surface caused by the crystallographic structure. Our investigations demonstrate the challenges of quantitative analysis of solute deuterium by APT but nevertheless provide insight to achieving the best possible experimental protocol.

To develop a direct production process for TiH 2 powder from TiO 2 , the reduction of TiO 2 using Mg in molten MgCl 2 – KCl salt under a high hydrogen chemical potential was investigated. The reduction of nano-sized TiO 2 powder was conducted at 973 – 1073 K under an Ar or Ar and 10% H 2 mixed gas atmosphere when the mass ratios of Mg to feed and salt to feed were 1.14 – 2.86 and 0.87 – 3.48, respectively. The results showed that the oxygen concentration in the Ti product decreased as the mass ratio of salt to feed and temperature decreased. Furthermore, according to the variation in Mg amounts, the oxygen concentration was 0.350 – 0.441 mass%. In addition, employing hydrogen during the reduction enhances the capability to decrease the oxygen concentration in the Ti product. Moreover, the hydrogen concentration in the Ti product increased as the amount of molten salt decreased, thereby enabling pure TiH 2 production. As a result, TiH 2 powder with an oxygen concentration of 0.350 mass% was obtained under a certain condition. These results demonstrate the feasibility of the direct production of low-oxygen TiH 2 powder from TiO 2 via reduction at 973 K using Mg in an Ar and H 2 mixed gas atmosphere.

This paper highlights the influence of titanium hydride particle on the rheological behaviour of nickel-titanium feedstock used in the metal injection process. The ratio of 50at% nickel and 50at% titanium hydride with 2 different powder loadings (65.5vol% and 67.5vol%) were investigated. A Rosand RH2000 capillary rheometer was used to determine the flow behaviour of feedstocks. The feedstocks were characterized at different temperature ranging from 150°C and 170°C and shear rate ranging from 50/s and 4442.63/s. The results showed on pseudo-elastic behaviour flow of NiTi feedstock which is suitable for injection moulding process.

Context In order to obtain environmentally friendly emulsion explosives formulations with higher power, based on zero oxygen balance, formulations of titanium hydride (TiH 2 )—high-power emulsion explosives were optimally designed. The results show that the zero oxygen balance formulation produces almost no toxic and harmful gases. The detonation temperature and detonation heat are increased. And the detonation volume decreases along with the increase in the content of TiH 2 . Zero oxygen balance formulation can effectively enhance the explosive power of TiH 2 -type high-power emulsion explosives compared to traditional formulations while improving its environmental friendliness and safety. This paper provides a basis for further development of the optimal brisance and environmentally friendly explosive formulations. Methods The principle of zero oxygen balance was applied to theoretically design the formulations of titanium hydride (TiH 2 )—high-power emulsion explosives. To find a zero-oxygen balanced formulation with the best detonation performance, Hess’s Law and Cast’s Law were used to calculate the detonation parameters such as detonation heat and detonation temperature. Also, the B-W method was used to anticipate the detonation products Graphical Abstract

Aluminum foams have emerged as a remarkable engineering material, exhibiting exceptional structural performance and many excellent properties. This has led to a rise in their application in various fields. The investigation and development of aluminum foam have led to the discovery of multiple applications in numerous industries, including the aerospace, automotive, petrochemical, and building materials industries. Foam made of aluminum, one of the most well-known examples of metallic foams, is a significant technological advancement in the foams industry. This article aims to comprehensively analyze the manufacturing techniques that employ blowing agents, such as alumina, titanium hydride, and sodium chloride. This article explores the unique properties and diverse applications of aluminum foams. In addition, the current status of research and development in aluminum foam is discussed. It accomplishes this by providing an overview of existing developments and identifying future opportunities in this industry. This review article is an invaluable resource for academics and industry professionals interested in aluminum foams, as it provides valuable insights into production procedures, properties, applications, and ongoing research.

The effects of the secondary processes of Hot Isostatic Pressing (HIP) at 920 °C and Heat Treatment (HT) at 1000 °C of Electron Beam-Melted (EBM) Ti–6Al–4V alloy on the microstructure and hydrogen embrittlement (HE) after electrochemical hydrogen charging (EC) were investigated. Comprehensive characterization, including microstructural analysis, X-ray diffraction (XRD), thermal desorption analysis, and mechanical testing, was conducted. After HIP, the β-phase morphology changed from discontinuous Widmanstätten to a more continuous structure, 10 times and ~1.5 times larger in length and width, respectively. Following HT, the β-phase morphology changed to a continuous “web-like” structure, ~4.5 times larger in width. Despite similar mechanical behavior in their non-hydrogenated state, the post-treated alloys exhibit increased susceptibility to HE due to enhanced hydrogen penetration into the bulk. It is shown that hydrogen content in the samples’ bulk is inversely dependent on surface hydride content. It is therefore concluded that the formed hydride surface layer is crucial for inhibiting further hydrogen penetration and adsorption into the bulk and thus for reducing HE susceptibility. The lack of a hydride surface layer in the samples subject to HIP and HT highlights the importance of choosing secondary treatment process parameters that will not increase the continuous β-phase morphology of EBM Ti–6Al–4V alloys in applications that involve electrochemical hydrogen environments.

The use of titanium hydride as a raw material has been an attractive alternative for the production of titanium components produced by powder metallurgy, due to increased densification of Ti compacts, greater control of contamination and cost reduction of the raw materials. However, a significant amount of hydrogen that often remains on the samples could generate degradation of the mechanical properties. Therefore, understanding decomposition mechanisms is essential to promote the components’ long life. Several studies on titanium hydride (TiH2) decomposition have been developed; nevertheless, few studies focus on the effect of the alloying elements on the dehydrogenation process. In this work, the effects of the addition of different amounts of Fe (5 and 7 wt. %) and Nb (12, 25, and 40 wt. %) as alloying elements were evaluated in detail. Results suggest that α→β transformation of Ti occurs below 800 °C; β phase can be observed at lower temperature than the expected according to the phase diagram. It was found that β phase transformation could take place during the intermediate stage of dehydrogenation. A mechanism was proposed for the effect of allying elements on the dehydrogenation process.

Magnetron-sputtered thin films of titanium and zirconium, with a thickness of 150 nm, were hydrogenated at atmospheric pressure and a temperature of 703 K, then anodized in boric, oxalic, and tartaric acid aqueous solutions, in potentiostatic, galvanostatic, potentiodynamic, and combined modes. A study of the thickness distribution of the elements in fully anodized hydrogenated zirconium samples, using Auger electron spectroscopy, indicates the formation of zirconia. The voltage- and current-time responses of hydrogenated titanium anodizing were investigated. In this work, fundamental possibility and some process features of anodizing hydrogenated metals were demonstrated. In the case of potentiodynamic anodizing at 0.6 M tartaric acid, the increase in titanium hydrogenation time, from 30 to 90 min, leads to a decrease in the charge of the oxidizing hydrogenated metal at an anodic voltage sweep rate of 0.2 V·s−1. An anodic voltage sweep rate in the range of 0.05–0.5 V·s−1, with a hydrogenation time of 60 min, increases the anodizing efficiency (charge reduction for the complete oxidation of the hydrogenated metal). The detected radical differences in the time responses and decreased efficiency of the anodic process during the anodizing of the hydrogenated thin films, compared to pure metals, are explained by the presence of hydrogen in the composition of the samples and the increased contribution of side processes, due to the possible features of the formed oxide morphologies.