Titanium Aluminum Alloy Research Articles

Modern and future schemes of very-high cycle fatigue tests

The development of a new piezoelectric fatigue machine operating in pure torsion is presented in this paper. The proposal for implementation of a testing machine to research on very-high cycle fatigue at biaxial bending is studied. Results of pure torsion tests on titanium alloy VT3-1 processed by forging and extrusion are shown. Evaluations of specimens shapes made of aluminum alloy D16T and titanium alloy VT3-1 were conducted as well as the possibility to conduct VHCF bi-axial bending tests was confirmed.

Temperature Effect on Stacking Fault Energy and Deformation Mechanisms in Titanium and Titanium-aluminium Alloy

Alloying elements have great influence on mechanical properties of metals. Combining dislocation characterization and in-situ transmission electron microscope straining at ambient and liquid-nitrogen temperature in high-purity titanium and Ti-5at%Al, we investigated the modulation of Al on dislocation behaviours as temperature changed. It reveals that segregation of Al at edge dislocation cores in Ti-5at%Al generates strong obstacles, promoting room temperature cross-slips. However, the effect of Al on reducing stacking-fault energy (SFE) as decreasing temperature is significant. Consequently, the lower SFE in Ti-5at%Al results in ordinary planar dislocation slip while massive dislocation cross-slips occurred in Ti at liquid-nitrogen temperature.

Investigation of Ti6Al4V and AA7075 alloy embedded nanofluid flow over longitudinal porous fin in the presence of internal heat generation and convective condition

The thermal attributes of porous fin due to radiation and natural convection have been carried out in the presence of nanofluid flow. The geometry of the fin taken for the analysis is rectangular profiled longitudinal fin. The temperature-dependent internal heat generation condition is also considered along with Darcy’s model. The two types of nanofluid containing titanium alloy () and aluminium alloy (AA7075) immersed in water is considered for the investigation. The modelled nonlinear ordinary differential equation is numerically solved by the Runge–Kutta–Fehlberg technique. The impact of geometric parameter on the heat transfer analysis of the fin due to the flow of both nanofluids is plotted and consequences are physically interpreted. It is observed that the presence of the water-based titanium alloy better enhances the fin heat transfer rate.

Application of MIG and TIG Welding in Automobile Industry

Emission and weight reduction have been identified over the years by the automobile industries as the most efficient ways to maintain fuel economy and to meet the demand of the government agencies on global warming. These challenges of reducing emission and weight are even being compounded with consumers taste for luxury features which adds to the weight of the traditional vehicle designs. To meet these demands, alloys such are Aluminium Alloys, Magnesium Alloys and Titanium Alloys have been identified as the suitable materials to replace conventional steel structures due to their superior properties such as high strength-to-weight ratio, high tensile strength and high-temperature performance. With the identification of suitable materials to replace the traditional materials, the welding of alloy materials remains a challenge faced by vehicle manufacturers. Although electron beam welding, ultrasonic welding and friction stir welding have proven to give quality weld joints of alloys used in automobile fabrication, their application is limited by the high cost of equipment, need for vacuum environment in electron beam welding, size and shape of base metals. Laser welding with its reduced heat affected zone (HAZ), good seam appearance and deep penetration has widely been applied in an automobile. However, it is not with its own shortcomings such as poor gap bridging capability, difficulty in welding reflective materials and high cost. Arc welding with its low cost compared to other welding techniques and high energy efficiency, therefore, remains a useful welding process in an automobile. In this paper, a review of the various investigations by researchers on MIG and TIG welding of alloys used in the automobile have been documented.

Effect of Sliding Velocity and Normal Applied Load on Wear Behavior of Al-Ti- Sic Composites for Automobile Brake Pad System Under Dry Sliding Condition

The wear and coefficient of friction (COF) behaviour of aluminium titanium (Al-Ti) alloys with varying of silicon carbide (SiC) are used as reinforcement material in the present research work. Automobile brake pads were developed by stir casting technique with 15, 20 and 25wt.% of SiC in Al-Ti alloys, respectively, instead of the traditional CI (cast iron) brake drum used for a chase machine. The normal applied load and sliding velocity varied to simulate vehicle running condition. It has been observed from the results the wear and COF for silicon carbide MMC is effectively than the CI material. The wear is varied with both sliding velocity and normal applied load. The experimental results reveals that the low wear was observed at 25wt.% of SiC than 15 and 20 wt.% of SiC. With increase of normal applied load, the wear was observed to increase whereas the COF decreases.

Topological Design of a Lightweight Sandwich Aircraft Spoiler.

In this study, a lightweight sandwich aircraft spoiler (AS) with a high stiffness-to-weight ratio was designed. Excellent mechanical properties were achieved by the synthetic use of topology optimization (TO), lattice structure techniques, and high-performance materials, i.e., titanium alloy and aluminum alloy. TO was first utilized to optimize the traditional aircraft spoiler to search for the stiffest structure with a limited material volume, where titanium alloy and aluminum alloy were used for key joints and other parts of the AS, respectively. We then empirically replaced the fine features inside the optimized AS with 3D kagome lattices to support the shell, resulting in a lightweight sandwich AS. Numerical simulations were conducted to show that the designed sandwich AS exhibited good mechanical properties, e.g., high bending rigidity, with a reduction in weight by approximately 80% when compared with that of the initial design model. Finally, we fabricated the designed model with photosensitive resin using a 3D printing technique.

Computer-aided detection of the optimal spraying modes of coatings based on intermetallic titanium-aluminum alloys

The computational experiments results on simulation of a layered structure formation and the prediction of characteristics (porosity, roughness, adhesion) of metallic coatings based on intermetallic titanium-aluminum alloys (α2-Ti3Al, γ-TiAl and TiAl3) are given. The coatings under conditions typical of atmospheric plasma spraying (APS) and for high-velocity spraying (HVOF, D-Gun Spraying, etc.) by computer-aided design have been prepared. The ranges of the “key physical parameters (KPPs)” values of the sprayed particles, which ensure the stable formation of spreading and solidified melt particles (splats) on the sprayed surface for each of the three types of intermetallic titanium-aluminum coatings, have been detected. Taking into account the stable splat formation conditions, as well as the minimum of porosity (and roughness) and the maximum adhesion strength of the simulated coatings, the optimal spraying modes of coatings based on intermetallic titanium-aluminum alloys (Ti3Al, TiAl and TiAl3) were determined.

The formation and Kr-ion irradiation behaviour of new microstructural features in additively manufactured titanium aluminium alloy

New microstructural features were found in the TiAl alloy manufactured using the gas tungsten arc welding-based additive manufacturing technology. The ion-irradiation responses of the new microstructure features were investigated in-situ via irradiation with 1 MeV Kr2+ ions at room and 873 K. Examination of the microstructure showed that the typical lamellar microstructure consisting of α2-Ti3Al and γ-TiAl phases formed α2/γ lamellar interfaces and γ/γ twin boundaries. Apart from this, the γ lamellae were also found to form γ/γ lamellar boundaries with the two γ lamellae in the same orientation or the <10-1 > //<411> orientation relationship. This is not observed in the TiAl alloys fabricated using traditional alloy fabrication methods. Kr ion-irradiation at room and elevated temperatures resulted in no significant difference in the morphologies of most radiation-induced defects in the <411> orientated γ lamellae and the <10-1> orientated γ lamellae. However, the areas of the new boundaries exhibited different damage morphologies in comparison with the traditional γ/γ twin boundaries. The formation mechanisms of the new microstructural features formed in the additive manufacturing process and their irradiation behaviour are investigated and discussed.

Investigation of the Mechanism of Precipitation of the Ti3Al in Two-Phase Titanium-Aluminium Alloy

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Correlation of Oxygen and Aluminum Contents of Molten Titanium-Aluminum Alloys in Alumina and Calcia Crucibles

As a key part of investigating a new proposed Ti-alloy production process, Ti-Al alloys were produced by aluminothermic reduction experiments at 1973 K in Al2O3 crucibles. Besides, pure Ti and Al were melted inside CaO crucibles at 1973 K to investigate the possibility of melt refining in equilibrium with CaO. The experiments were carried out in a vacuum induction furnace under argon gas at atmospheric pressure. The experimental results were proved by thermodynamic evaluations including also literature data. The correlation of oxygen and aluminum in Ti melt with 11 to 23 wt pct Al in contact with Al2O3 was assessed as $$ 3\ln X_{\text{O}} = -\,2\ln X_{\text{Al}} - 9.1 \pm 0.4. $$ This correlation in Ti melt with 3 to 10 wt pct Al in contact with CaO was $$ 3\ln X_{\text{O}} = - \,2\ln X_{\text{Al}} - 14.9 \pm 0.3. $$ Partial molar excess Gibbs free energies of mixing and combinations thereof in Ti-rich Ti-Al-O-Ca melt were assessed as $$ RT \ln (\gamma_{\text{Al}}^{2} \cdot \gamma_{\text{O}}^{3} ) = - 894 \pm 6\,({\text{kJ}}/{\text{mol}}) $$ , $$ RT \ln \left( {\gamma_{\text{Ca}} \cdot \gamma_{\text{O}} } \right) = - 195 \pm 4\,({\text{kJ}}/{\text{mol}}) $$ , $$ RT \ln \gamma_{\text{O}} = - 258 \pm 6\,({\text{kJ}}/{\text{mol}}) $$ , $$ RT \ln \gamma_{\text{Ca}} = 62 \pm 7\,({\text{kJ}}/{\text{mol}}). $$ The activity of Al2O3 in CaO-saturated slag was assessed as 0.003 ± 0.001. The changes of Gibbs free energy for the dissolution of 1 wt pct oxygen and 1 wt pct calcium in Ti-Al melt were estimated as −630 ± 6 and −11 ± 7 (kJ/mol), respectively. A model was developed and applied to calculate the basic data for refining Ti-Al alloy.

Key factors and developmental directions with regard to metal additive manufacturing

Metal additive manufacturing is a new type of material-forming technology characterized by its short process and near net shape. Equipment, material and process are critical factors which serve as the supporter, key, and foundation respectively in terms of the development of this technology. In this paper, the characteristics of the equipment, material, and process of the different representative technologies were summarized. The relations among metal additive manufacturing equipment, manufacturing material, and manufacturing process as well as their roles in the metal additive manufacturing technology were analyzed. The research status of the raw material supply system, forming system, and control system were reviewed. The typical microstructure and mechanical properties of metal additive manufacturing materials, such as titanium alloy, nickel alloy, aluminum alloy, and steel, were summarized. The effects of the manufacturing process parameters on residual stress, porosity, accuracy, and microstructure were discussed. Problems associated with the manufacturing equipment, such as high cost, limited forming size, and low forming efficiency were discussed along with the problems associated with the material, such as high production cost and poor applicability. Furthermore, problems associated with the metal additive manufacturing process, such as difficult matching of process parameters and severe thermal accumulation, were elaborated as well. Future developmental goals in metal additive manufacturing include: (a) reducing the cost of manufacturing equipment and material, (b) expanding the range of product forming size, (c) improving the product printing accuracy and forming efficiency, (d) expanding the types and application scope of metal additive manufacturing material, (e) reducing the difficulty in the matching of process parameters, (f) improving product quality and comprehensive performance, and (g) developing new types of metal additive manufacturing technologies.

Ti &lt;sub&gt;3&lt;/sub&gt;Al Baded Alloy Reinforced by SiC Whiskers: Core-Shell Structure, Interface Nanotwins and Mechanical Properties

Thermal deformation nowadays is a general fabrication method for Titanium-Aluminum alloy, which could enhance the mechanical properties due to the refining of grain size and lamellar colonies combined with the deformation induced nanotwins. Compared with thermal deformation method, here we report a casting strategy which realizes the ideal refining, nanotwinning combined with efficient strengthening and toughening in a Ti3Al matrix alloy. Average lamellas width are refined from about 3.3μm to about 37nm. Samples exhibit an ultimate compressive strength of 2.76GPa with a strain about 17.3%. SiC-Nb4C3 core-shell structure was observed in the interface between reinforcement and matrix. Nanotwins of {0002}α2-Ti3Al in the diphasic interface exhibit an unusual three-dimensional morphology, which is related to the deformation of TiAl phase and the incomplete phase transition.

Machinablity improvement with ultrasonic vibration–assisted micro-milling

An ultrasonic vibration–assisted micro-milling with horizontal vibration of workpiece is investigated in this article. A vibration platform with maximum amplitude of 15 μm based on universal ball support structure is designed and built by our group. Titanium alloy TC4 and aluminum alloy 6061T6 were chosen as workpiece material. Series of slot-milling experiments were conducted with and without vibration at different amplitudes and feed rates to explore the effects of vibration on the micro-milling. Experiment results showed that ultrasonic vibration can effectively reduce milling force by 12% and 17%, respectively, for aluminum alloy 6061T6 and titanium alloy TC4 compared with that of conventional milling and hence leading to a better machining accuracy and longer tool life. Furthermore, the effect of ultrasonic vibration on titanium alloy is much more obvious. The topographies of machined surfaces also showed that ultrasonic vibration can reduce surface defects and machining marks and thus improve the surface quality for both 6061T6 and TC4. Besides these, it is worth to be noted that ultrasonic vibration leads the size effect point appear at much lower feed rate than conventional milling, which means vibration brings a change to machining mechanism and delays the appearance of micro-milling.

Development of Lightweight Aluminum-Titanium Alloys for Aerospace Applications

Aluminum (Al) and Titanium (Ti) based lightweight alloys have been a topic of discussion and research for a few decades now. Resulting alloys with hard intermetallic phases in Al-Ti binary system have good microstructural and mechanical properties including low densities, high specific strength, better resistance against oxidation and corrosion which are highly desirable in aerospace industry. Such an alloy system was studied in our research. Powder metallurgy (PM) was used as processing route because of its economical and easy operation. Samples were prepared using metallic powders of Aluminum (Al) and Titanium (Ti) with varying compositions of 95 at.% Al-Ti, 90 at.% Al-Ti and 88 at.% Al-10 at.% Ti-2 at.% SiC. After compaction, pressureless sintering was carried out at 620°C for several hours in Argon atmosphere followed by annealing resulting in a reasonably dense Al-Ti alloy. Microstructure and phase composition of alloy was analyzed by Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS), respectively. Hardness was evaluated by Vickers micro indentation test. An increase in hardness was observed. Sample containing reinforcement particles (SiC) demonstrated highest value of hardness.

The technical development of titanium alloy surface process using electrochemical abrasive jet machining

PurposeThis paper aims to develop an electrochemical abrasive jet machining (ECAJM) technology to investigate the surface machining effect of Ti-6Al-4V alloy.Design/methodology/approachFirst, the ECAJM equipment was set up, and a series of experiments for the surface machining of Ti-6Al-4V alloy was performed.FindingsThe experimental results show that the flowing abrasives of 0.05 Wt.% can effectively remove the TiO2 oxide film of Ti-6Al-4V alloy surface. In addition, the flowing abrasives produce cutting machining effect on the surface of titanium aluminum alloy, and the oxide film can be removed effectively. For the case of machining pressure of 0.4 Mpa and machining gap of 0.4 mm, the processing efficiency can be achieved up to 20 µm/s.Originality/valueUnder different machining pressure, the flowing abrasive with high kinetic energy impacting the Ti-6Al-4V alloy surface and the oxide film produced from the electrolytic reaction process can be removed effectively, thereby enhancing the efficiency of electrochemical machining process.

A Comparative Study of Graphite Growth in Cast Iron and in Analogous Systems

Crystallization of graphite during the solidification and cooling of cast iron to room temperature has been the object of relentless, yet often inconclusive research. The importance of the subject cannot be underestimated, as graphite morphology is a major player in establishing the mechanical and physical properties of cast iron. Graphite crystallization is a complex phenomenon controlled by melt composition, local melt supersaturation, melt temperature and temperature gradient (cooling rate). All these are wide-ranging variables in the casting process. The results of a major effort to understand the complexity of graphite crystallization in cast iron is presented in this comparative study of crystal growth in materials with crystal morphologies similar to that of graphite. The analysis includes that of analogous materials such as eutectic aluminum–silicon and nickel carbon alloys, growth of other hexagonal or tetragonal crystals such as ice crystals and Al3Ti in aluminum–titanium alloys, growth of graphite through other processing routes such as chemical vapor deposition (a gas-to-solid transformation), and heat treatment of carbon steel (a solid-to-solid transformation), and the previous information on the crystallization of carbon in cast irons. An exhaustive analysis of the most widely accepted models for graphite growth is also presented.

Влияние скорости деформации на тепловыделение при квазистатическом растяжении металлов. Эксперимент

AbstractThe paper presents the results of experimental studies of energy dissipation during a quasi-static stretching of metals and alloys at room temperature. The strain rates varied in the range of 10^–3–10^–2 s^–1. Samples of M1 copper, AZ31B magnesium alloy, BT6 titanium, 12Cr18Ni10Ti steel, and D16AM aluminum alloy were analyzed. The experimental results demonstrated a significant dependence of the heat release on the strain rate in the absence of its influence on stress–strain diagrams for all the metals studied in this range of strain rates. The correlation of the changes in the character of heat release with the processes of structural transformations at various stages of plastic flow is shown on the qualitative level. A difference in the nature of the processes of heat release in materials with different ratios of the plasticity and strength is noted.

Research Results Of Stress-Strain State Of Cutting Tool When Aviation Materials Turning

Titanium alloys and stainless steels are hard-to-machine of all the machining types. Cutting edge state of turning tool after machining titanium and high-strength aluminium alloys and corrosion-resistant high-alloy steel has been studied. Cutting forces and chip contact arears with the rake surface of cutter has been measured. The relationship of cutting forces and residual stresses are shown. Cutting forces and residual stresses vs value of cutting tool rake angle relation were obtained. Measurements of residual stresses were performed by x-ray diffraction.

Robotic edge machining with abrasive brushes

The article describes application of an industrial robot with an electric spindle for finish machining of parts made from aluminum alloy V95pchT2 and titanium alloy VT-20 using abrasive brushes. Effects of cutting velocity, brush deformation and supply on machining performance (edge size) and surface quality (positioning and roughness) have been identified. Based on the experimental data, mathematical dependencies have been developed.

Influence of laser parameters in surface texturing of Ti6Al4V and AA2024-T3 alloys

Laser texturing can be used for surface modification of metallic alloys in order to improve their properties under service conditions. The generation of textures is determined by the relationship between the laser processing parameters and the physicochemical properties of the alloy to be modified. In the present work the basic mechanism of dimple generation is studied in two alloys of technological interest, titanium alloy Ti6Al4V and aluminium alloy AA2024-T3.Laser treatment was performed using a pulsed solid state Nd: Vanadate (Nd: YVO4) laser with a pulse duration of 10 ps, operating at a wavelength of 1064 nm and 5 kHz repetition rate. Dimpled surface geometries were generated through ultrafast laser ablation while varying pulse energy between 1 µJ and 20 µJ/pulse and with pulse numbers from 10 to 200 pulses per spot. In addition, the generation of Laser Induced Periodic Surface Structures (LIPSS) nanostructures in both alloys, as well as the formation of random nanostructures in the impact zones are discussed.