The thermal expansion coefficient (CTE) is a vital design parameter for reducing the thermal-stress-induced structural failure of electronic chips/devices. At the micro- and nano-scale, the typical size range of the components in chips/devices, the CTEs are probably different from that of the bulk materials, but an easy and accurate measurement method is still lacking. In this paper, we present a simple but effective method for determining linear CTEs of micro-scale materials only using the prevalent nanoindentation system equipped with a heating stage for precise temperature control. By holding a constant force on the sample surface, while heating the sample at a constant rate, we measure two height–temperature curves at two positions, respectively, which are close to each other but at different heights. The linear CTE is obtained by analyzing the difference of height change during heating. This method can be applied to study the size effect or surface effect of CTE of embedded micro-scale structures, aiding the failure analysis and structural design in the semiconductor industry.

Surface modification of titanium and titanium alloys is a common method to improve anchoring of bone tissue and implants in hard tissue engineering applications. In the current work, a combination of chemical and physical methods (anodization and physical vapor deposition) was used to roughen the titanium surface and deposit iron (Fe) on the surface of titanium at different thicknesses. The optimized thickness of 100 Å was selected for mechanical and biological characterization. We found that anodization increases the surface roughness of Ti from 21 ± 0 to 229 ± 9 nm, whereas Fe deposition does not change it significantly. Our results also showed that surface modification of Ti by anodization increases the proliferation of osteosarcoma cells at both time points, whereas Fe-deposited samples showed the lowest cellular activity. These results suggest that Fe-deposited Ti implants may be suitable candidates for patients with osteosarcoma, as the proliferation of malignant cells decreases in the presence of Fe.

The adoption of selective laser melting (SLM) for fabrication of porous titanium has resulted in many new investigations into the complex design parameters associated with porous architecture of high spatial resolution. The development of meta-materials has included research into the effects of unit cell architecture (strut versus sheet), porosity, pore size, and other factors on the performance of metallic scaffolds. The current study examined the interactive effects of varying the gyroid sheet unit cell size and overall specimen size on the compressive behavior of Ti–6Al–4V ELI porous scaffolds manufactured via SLM. The increasing unit cell size relative to specimen geometry was found to decrease the compressive strength and stiffness of the overall structure and shift the material fracture mode. The understanding of the relationship between unit cell size and specimen geometry can be used to optimize mechanical properties of implants with constrained volumes and pore/wall size requirements to optimize properties of porous titanium implants for strength and osseointegration.

Severe cracking and unsatisfied mechanical performance are the major challenges of manufacturing titanium aluminide (TiAl) components by selective laser melting (SLM). In this work, graphene oxide (GO) sheets were introduced onto the metal powder surface to improve the manufacturability of SLM of a Ti–48Al–2Cr–2Nb (at.%) alloy and enhance the mechanical strength of the laser-fabricated parts. The effect of laser power and GO content on the macromorphology of single-track processing was investigated, showing that the crack-free track could be obtained with the addition of 0.1–0.5 wt.% GO under a laser power of 110 W. In addition, the characterization of multilayer buildups via electron backscatter diffraction and backscatter electron imaging reveals the grain refinement during SLM of GO/TiAl nanocomposites. Finally, the strength of the as-built samples was examined using micro-hardness test, showing a maximal increase of 21.9% by adding 0.3 wt.% GO into the TiAl powders from laser-fabricated samples without GO.

The breakdown of the columnar grains and lamellar α + β colony microstructure in two-phase Ti alloys during conversion of ingot to billet is critical to the development of desired combination of mechanical properties. Colony breakdown occurs during a series of thermomechanical processing steps in the α + β phase field. However, fundamental knowledge of the microstructural dependence of this transformation is limited, particularly its dependence on the initial orientation of the α + β colony relative to the imposed strain-path. In this study, the viscoplastic self-consistent polycrystal plasticity model is used to examine deformation behavior as a function of crystal loading direction. Criteria were developed to predict relative globularization rates; it was found that both slip system activities in the α phase and relative crystal rotations of each phase must be considered. Predictions are demonstrated to be consistent with literature and suggest that further experimental investigation of relative globularization rates is necessary.

In this study, mechanical properties and microstructural investigation of Ti64 at high strain rate are studied using a split-Hopkinson pressure bar method under compression for temperatures up to 800 °C. Flow softening in the mechanical response of material to such loading conditions hints at instability in compression, which increases with an increase in temperature. Microstructural characterization of the deformed material is characterized using the electron-backscattered diffraction technique. It reveals the presence of instabilities in Ti64 in the form of a fine network of shear bands. The shear band width grows with an increase in temperature along with the area fraction of shear band in the material, displaying its improved capacity to contain microstructural instabilities at higher temperature. After a detailed microstructural investigation, a mechanism for shear band widening is proposed. Based on this mechanism, a path generating nuclei within shear bands is discussed.

Titanium and its alloys are probably the most suitable materials for selective laser melting (SLM) additive manufacturing to process. However, the high cost of raw powder materials limits the industrial application of as-printed Ti products. In this study, we have formulated a cost-affordable Ti–TiB composite powder for SLM, to simultaneously achieve excellent mechanical performance and cost effectiveness. The optimization of the processing parameters will be shown to lead to high relative density (99.3%) for the as-printed Ti–TiB composites containing (0.5, 1, and 2 wt%) TiB2. Furthermore, by incorporating TiB2, the as-printed composites exhibit much improved fracture strength (up to 1813 MPa) and microhardness (up to 412 HV), among which the Ti–0.5 wt% TiB2 has demonstrated a great combination of strength (1007 and 1646 MPa as yield and fracture strengths, respectively) and tensile ductility (~8%). The solidification pathway for the Ti–TiB composite during SLM has been investigated, and the underlying mechanism for achieving high yield strength is discussed based on existing models for shear-lag strengthening, grain refinement, and dispersion strengthening.

We describe experimental approaches to real time examination of the microstructural evolution of Ti 6%Al 4%V upon cooling from above the beta transus (~995 °C) while imaging in the scanning electron microscope. Ti 6%Al 4%V is a two phase, α+β titanium alloy with high strength and corrosion resistance. The β →α transformation on cooling can give rise to different microstructures and properties through various thermal treatments. Fully lamellar microstructures, bi-modal microstructures, and equiaxed microstructures can each be obtained by accessing different cooling rates upon the final treatment above the beta temperature, each resulting in uniquely enhanced material properties.

Utilizing the capabilities of a heating/ tensile stage developed by Kammrath & Weiss Inc., are able to apply real-time imaging techniques in the scanning electron microscope to monitor the development of the microstructure. Annealing temperatures up to 1100 °C are attainable, with cooling rates ranging from 0.1 ° C per second to 3.3 °C per second. This has allowed us to directly observe the formation of lamellae at different annealing temperature/ cooling rate combinations to determine the lamellar microstructure width, separation, and colony size.

Laser surface treatment is widely used as an engineering technique due to its special characteristics and several advantages over other surface modification techniques. In the present study, elemental mechanically pre-alloyed powder consisting of Niobium, Titanium and Nickel was deposited onto a grade 5 Titanium alloy substrates to form a high wear resistance coating. This was such that the surface mechanical properties of the base metal can be improved. The fabricated samples were characterised using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), Differential Scanning Calorimeter (DSC), micro hardness tester and wear machine. The deposited coatings were well bonded and consisted of various phases. Hardness was seen decrease with increase in Nb content while wear resistance increasing with increase in niobium content.

Various cases of medical implants produced through additive manufacturing (AM) in Ti6Al4V have been reported in literature. Not all manufacturing processes used, were qualified. In striving to deliver certified AM medical implants and devices, an ISO 13485:2016 quality management system was implemented in the Centre for Rapid Prototyping and Manufacturing (CRPM) of the Central University of Technology, Free State (CUT) in Bloemfontein, South Africa. This certification is valid for design, development and production of patient-specific custom-made titanium implants, preoperative models, jigs and cutting-guides in nylon through AM, and contract-production of these products. For maintaining this quality management system, the generation of data to validate the individual processes in the AM process-chain is crucial to prove the DMLS product-quality of CRPM’s products. During the past five years, directed research data was produced and published to prove that medical implants produced through DMLS can fully comply with the accepted international standards for material, physical, chemical and mechanical properties of such parts. The paper discusses the quality management system’s establishment; materials research projects executed to generate validation data are mentioned; and examples of customised titanium implants for restoring the quality of life of patients are shown.

Titanium (Ti) has been extensively used in medical devices owing to their low density, high strength, excellent corrosion resistance, and biocompatibility. However, thrombus formation and bacterial infections are still challenges for their application in specific clinical cases. Hence, we have developed a simple, efficient, and stable strategy that endow Ti with anticoagulant and antibacterial properties through chemical bonding and electrostatic bonding. A large number of hydroxyl groups were produced on the surface of Ti by annealing at 500 °C. Then, heparin was immobilized on annealed surface with chemical bonding and chitosan was captured in an electrostatically bound manner by simply soaking in solution. The results indicated that the surface-functionalized Ti exhibited excellent anticoagulant properties by a reduction in platelet adhesion and prolonged blood clotting time. Furthermore, the modified Ti also showed antibacterial properties against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

The system GeO2–TiO2 was studied experimentally at high pressure and temperature to measure the miscibility of the two components and to test its applicability as a temperature sensor in high-pressure experiments. Significant solubility between the two end-members was found, with two coexisting solid solutions at high pressure exhibiting mutual solubility that increases with temperature along a solvus. The two solid solution compositions at the solvus can be distinguished readily by X-ray diffraction. At higher temperatures, a complete solid solution exists between the two end-members. The complete solution occurs above a critical line in P–T space (a critical point at each pressure). The critical point is located near 1630 °C and mole fraction ${X_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}} = 0.57$ at 6.6 GPa and changes by 60 ± 5° per GPa in the region from 4 to 7 GPa. A model for the shape of the solvus is developed using X-ray diffraction data points from a series of quench experiments and an in situ experiment, and the model is used to estimate the thermal gradients in a Kawai-type multianvil assembly.

We highlight the current understanding of mechanisms of phase transformation, strengthening, and the role of alloying elements in aluminum, magnesium, and titanium alloys, including nucleation and growth of precipitates, precipitate–dislocation interactions, solute segregation at precipitate–matrix interfaces and planar defects, and the development of strengthening models that account for the real particle shape. Future directions such as atomic-scale elemental mapping and computation, and the influence of particle shape on mechanical properties are discussed. With the combination of advanced characterization and computational tools, it is anticipated that much less time will be needed to develop the next generation of light alloys.

The oxidation behavior of two percentages of TiB + TiC reinforced Ti–6Al–4V composites derived from Ti–B4C–C and Ti–TiB2–TiC systems was investigated at 873–1073 K for 320 h in air. The oxidation weight gain curves of the (TiB + TiC)/Ti–6Al–4V composites at 973 K basically obey parabolic law, while those at 873 and 1073 K mainly follow linear law and parabolic-linear law, respectively. The oxide layers of the composites are predominately found to be rutile TiO2, Al2O3, and the mixture of V2O3 and V2O5. The oxidation layers turn thinner with increasing the nominal volume fraction of reinforcements in the (TiB + TiC)/Ti–6Al–4V composites. Moreover, according to the calculation results of reaction index (n) and effective activation energy (Qeff) and the analyses of cross-sections of the oxidation layers, the oxidation resistance ability of the composites from Ti–TiB2–TiC system is higher than that from Ti–B4C–C system while employing the same sintering temperature and nominal volume fraction of reinforcement.

Surface properties of titanium implants are key factors for rapid and stable bone tissue integration. So, in order to promote the osseointegration of implants, various surface treatments have been proposed. The objective of these surface treatments is to improve protein adsorption, cell adhesion and differentiation, and consequently, the tissue integration of titanium implants. In this paper, we propose to describe and compare the different strategies available in the literature to produce micro- and nanostructured surfaces on titanium, especially the recent results using electrochemical anodization. Anodization is a cost-effective process that produces nanostructures based on the electrolytic growth of columnar titanium oxide layers. By mastering the electrolyte composition and voltage, a regular array of pores with controlled diameters ranging from 15 to 200 nm are easily produced. Then we will present the latest results on the osteointegration of the surface composed anodized titania nanotubes.

Plasmonic metallic nanoparticles can significantly enhance the catalytic efficiency of semiconductors via plasmonic photocatalysis. In this study, a hybrid Ag/TiO2 photocatalyst was synthesized and tested for the photochemical reduction of bicarbonate to value-added formic acid. It was found that under solar irradiation, TiO2 is not very efficient, but formate production is significantly increased with the addition of silver nanoparticles. Under 365 nm irradiation, the photocatalytic efficiency of TiO2 is enhanced, but no effect was observed with the addition of silver nanoparticles. Under solar irradiation, Ag/TiO2 reached an apparent quantum efficiency (AQE) of 7.78 ± 0.04%, the highest AQE observed so far. Enhanced photocatalytic activity is attributed to the synergistic effect between UV photon excitation of TiO2 and surface plasmon resonance enhancement. To elucidate the mechanism of plasmon-enhanced photocatalysis, experiments were performed under solar irradiation and 365 nm irradiation. We propose that photo-excited electrons are transferred from above the Fermi level of the metal nanoparticle to the conduction band of the semiconductor through plasmon-induced electron transfer.

Based on wettability and reaction interfaces previously reported, as well as on thermodynamic considerations, a likely mechanism has been proposed for the chemical interaction taking place at the metal/ceramic interface during wettability experiments carried out by the so-called “sessile drop” method. The experiments involved three Ag-Cu-based brazing alloys [Cusil (Ag-28wt.%Cu), Cusil-ABA (Ag-34.6wt.%Cu-1.58wt.%Ti) and Incusil-ABA (Ag-26.6wt.%Cu-12.4wt.%In-0.89wt.%Ti)] and as polished and pre-oxidized pressure-less sintered silicon carbide (PLS-SiC), with a total holding time of 90 minutes at 850 °C, under a Zr sponge-gettered vacuum of 10-4/10-5 Torr.

Given the potential of Titanium Dioxide in diverse areas including alternative energy, drug delivery and protein adsorption, it is imperative that the underlying mechanism of surface-water interactions be thoroughly understood. Interaction lifetimes between the surface and the surface-adjacent water molecules have a major bearing on interfacial behaviour. Our study employs Molecular Dynamics simulations to understand interfacial interactions of water with a Titanium Dioxide surface, with focus on these interfacial interaction lifetimes. Two polymorphs of Titanium Dioxide, Anatase (101) and Rutile (110) are studied.

Pseudo-α or near-α titanium alloys are being widely used in the power generation industry due to their stability at high temperature service, good mechanical characteristics and corrosion resistance. Particularly Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy is mainly used in turbines components, heat exchangers and pipes for steam conduction, among others; these are subjected to critical conditions of temperature, abrasion and corrosive environments. A good performance of such devices depends on the chemistry and of the material processing story.

Effects on microstructure and wear resistance with the addition of Ru and small variation of V and Mo amounts in the Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy were analyzed. Three different alloys were melted in a vacuum induction furnace with a cooled copper skull under an argon protective atmosphere for this study

Four alloys were melted “Alloy 1” Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C-0.3% Ru, “Alloy 2” Ti-6%Al-0.5%V-1.6%Mo-0.5%Zr-0.1% C-0.3% Ru, “Alloy 3” Ti-6%Al-2.2%V-0.5%Mo-0.5%Zr-0.1%C-0.3%Ru. After melting, all alloys were homogenized at 1200°C for two hours, followed by hot rolling above β transition temperature with a reduction of 50% in thickness.

All alloys were analyzed by using scanning electron microscopy (SEM) and Vickers Micro hardness (HV). Results shown that Mo and V variations modified the micro hardness by microstructure refinement. In contrast, the addition of Ru showed no microstructure modification.

Nanoparticles of titanium dioxide (TiO2), synthesized by the sonochemical technique, were mixed with different amounts of graphene oxide (GO), obtained by the improved method of Hummer, in order to modify their bandwidth. The TiO2/OG compounds were characterized using different techniques: X-ray Diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-Vis-NIR spectroscopy. TiO2 bandgap decreased, with GO incorporation, from 3.2 to 2.72 eV when GO was present at 20 weigh percentage (TiO2/GO-20%). Photodegradation experiments of methylene blue (MB) were performed with the materials to verify their photocatalytic activity. At 40 minutes, the pure TiO2 degraded 48% of MB, whereas the compound TiO2/GO-20% degraded 88%, showing a good incorporation of both compounds and the improvement of TiO2 photocatalitic properties.