Papers by Keyword: TiAl

Abstract: In order to prepare a highly oxidation-resistant surface for TiAl and SUS 304 stainless steel, the molten salt electrodeposition of Al or Y on these metals was carried out. The electrodeposition was conduced using a potentiostatic polarization method at constant potentials in an equimolar NaCl-KCl melt containing AlF3 or YF3 at 1023 K. After the Al electrodeposition, homogenous deposit layers were formed on the TiAl and the stainless steel. The deposited layer formed on the TiAl consisted of TiAl3. The deposited layer formed on the stainless steel consisted of some Fe aluminides. The TiAl and the stainless steel covered by the electrodeposited layers were far more resistant than the bare TiAl and stainless steel to high temperature oxidation. The Y electrodeposition on the stainless steel induced the deposition of Y particles on the stainless steel. The cyclic-oxidation resistance of the electrodeposited stainless steel was remarkably improved as compared to the untreated stainless steel.

Abstract: To solve the problems caused by high temperature in the cutting zone during high-speed milling of Titanium alloys, some cooling methods are employed, such as cold air cooling, high pressure coolant jet impinging, MQL, etc. But all have their shortfalls, both in cooling efficiency and environmental pollution. Here a new high efficiency cooling technology-cryogenic pneumatic mist jet impinging (CPMJI) cooling technology is offered. In this technology, a little quantity of coolant is carried by high pressure cryogenic air (-20
) and reaches the machining zone in the form of mist jet. This paper mainly focuses on the cooling effects of CPMJI in high-speed milling of Titanium alloy Ti-6Al-4V, as compared with dry, cold air cooling and MQL conditions. CPMJI greatly reduced the temperature in cutting zone and flank wear of tool.

Abstract: Cutting temperature has direct effects on tool wear and tool life, as well as machining accuracy and machining quality. Titanium alloys, however, are generally machined at lower cutting speeds with cemented carbide tools due to its low thermal conductivity and high chemical reactivity with cutting tool materials. This paper deals with cutting temperature in high-speed milling of a near alpha titanium alloy. The measuring principle of cutting temperature by the workpiece-constantan thermocouple method was illustrated and the physical meaning of the electromotive force (EMF) signals was described in the paper. The effects of cutting parameters and wear status on cutting temperature were studied, and the temperature distribution along the cutting edge was investigated.

Abstract: The surface treatment for TC4 alloy was conducted by MEVVA ion implantation method. The corrosion resistance of TC4 alloy implanted by La+, Mo+ were measured. It were found that Mo ion implantation improved corrosion resistance of TC4 alloy in acidic chloride solution, but La ion implantation gave the opposite result because they have different chemical activity. The more implanted dose of Mo+, the more improvement of corrosion resistance.

Abstract: Titanium alloy has been used as a material for orthopaedic implants, however drawbacks still exist. Considerable efforts have been taken to modify the surface structure of the implant material and improve the biological performance. Previously we have demonstrated that biomaterials surface modification has a significant effect on the regulation of osteogenesis. We have investigated the behaviour of human osteoclasts on sol-gel coated carbonated hydroxyapatite on anodized titanium alloy. Osteoclasts cultured on the modified surface were able to attach and spread, exhibiting the characteristic peripheral brush border. Successful differentiation of the monocytes into osteoclasts and their attachment to the coated surface and the formation of resorption-like imprints indicated that carbonate hydroxyapatite (CHAP) coated titanium alloy play a significant role in regulating the functional activity of osteoclasts.

Abstract: The purpose of this study is to determine the potential of the LEBRA-PXR imaging in investigating the details of newly formed bone around the dental implants. Transmission image observation of the undecalcified specimen at the wavelength of 1.771 Å showed clearly the formation of immaturely calcified new bone around the dental implants which could not be observed in the usual CMR nor conventional X-ray imaging apparatus.

Abstract: As TiAl based alloys begin to approach maturity, the development of successful and cost effective joining methods will be required. The growing industrial interest in these materials, particularly in aerospace and automotive industry, led to an interesting challenge - how to joint parts and components in order to produce integrated and resistant structures. Diffusion bonding of materials produces components with thinner interfaces than other joining techniques do. The absence of abrupt microstructure discontinuity and the small deformation induced maximize joint strength. This work focuses on the joining of TiAl using a thin multilayer obtained by alternating nanometric layers of titanium and aluminium. The Ti/Al layers were deposited onto the γ-TiAl samples by DC magnetron sputtering. The interfaces of these diffusion bonded joints depend on processing and deposition conditions. In this work we describe the influence of bilayer thickness (period) and on microstructure and chemical composition of the joining interfaces.

Abstract: In this work, a lightweight Ti-10Mg-5Al (wt. %) alloy for structural components was produced by mechanical alloying. A metastable α-Ti(Al,Mg) solid solution was obtained after 50h of milling. Diffraction peaks ascribed to the Mg phase were detected in the XRD pattern of the sample heat treated at 600°C. This phase tends to oxidize with the increase of temperature giving rise to MgO. The structure of the mechanically alloyed and 900°C heat treated sample consisted of a Ti(Al) solid solution with dispersed MgO particles in the matrix. Hardness and Young’s modulus values obtained from ultramicrohardness tests confirm the strength improvement of the Ti-based alloy due to the MgO reinforcement.

Abstract: Investigation of the microstructure, properties and biocompatibility of the Ti-6Al-4V alloy nitrided under glow discharge was performed. The microstructural analyses were carried out using light microscopy, X-ray diffraction, analytical scanning and transmission electron microscopy. Phase identifications and chemical composition of the layer and bulk material (substrate) were determined by electron diffraction and energy dispersive X-ray spectrometry. Atomic force microscopy was applied for layer surface topography measurements. Microhardness and Young’s modulus measurements as well as frictional wear resistance and corrosion resistance tests were performed. The investigation revealed a clear correlation between the micro/nanostructure and surface topography of the layer with its micromechanical, tribological and corrosion properties. In-vitro examinations of biofilm and cell behaviour show that the nitrided Ti-6Al-4V alloy exhibits good biocompatibility.