Papers by Keyword: Ti-Based Alloys

Abstract: The microstructural characterization of a fan blade of an aircraft gas turbine, manufacturing of Ti-6Al-4V alloy, was conducted in order to evaluate the occurrence of internal damage. The blade analyzed was removed from aeronautical service. An analysis was carried out by using X-ray computed microtomography and scanning electron microscopy in three samples obtained from the tip and the root of the blade, as well as from its midsection, along its length. These results were compared with those obtained through the microstructural characterization by optical microscopy of specimens, approximately of 15×5×4 mm. The results show the occurrence of early-stage erosive wear on the component and morphological changes of the alpha-grains of Ti-6Al-4V alloy, in comparison with those reported in literature. These changes were observed in the longitudinal and transverse sections of specimens of the blade, which could be related to the mechanical stresses which these elements are subjected during their aeronautical service. The results obtained by X-ray computed microtomography did not show evidence of internal cracking. Finally, the morphological changes identified in the alpha-grains may be a critical parameter to removing these important components from service. Additionally, the use of the open-source software 3D Slicer for the reconstruction of images from X-ray computed microtomography may become a viable and valuable option for the analysis of data obtained by mean of this technique.

Abstract: Mechanical alloying (MA) is a simple and versatile dry powder processing technique that has been used for the manufacture of both equilibrium and metastable phases of commercially useful and scientifically interesting materials. It owes its origin to an industry need to develop a nickel-based super alloy for gas turbine applications that had both oxide dispersion strengthening and precipitation hardening. This far-from equilibrium powder metallurgy processing technique involves fracturing, welding and re-welding of powder particles in a High Energy Ball Mill (HEBM). MA is an economically viable process with important technical advantages. Its utmost advantage is in the synthesis of novel alloys, e.g., alloying of ordinarily immiscible elements, that is not possible by any other technique. As MA is a completely solid-state processing technique, the limitations imposed by phase diagrams do not apply to it. The MA process is capable of producing different types of metastable effects in a variety of alloy systems. Some of the metastable effects achieved by MA are solid solution formation and amorphisation. MA has the possibility of producing superior and enhanced materials than those produces by conventional methods. In this work a review of MA and its present and potential applications for Ti-based materials are presented.

Abstract: Ti and Ti-based alloys have favorable properties for biomedical applications, such as high specific strength, low Young’s modulus, excellent corrosion and wear resistance, and good biocompatibility. The addition of alloying elements and heat treatments can result in a good combination of properties. Mo and Zr are β-stabilizer elements that decrease the Young’s modulus and increase the mechanical strength and corrosion resistance. Oxygen is an interstitial element that can improve mechanical strength and prevent ω phase formation. In this study, we analyzed the influence of substitutional and interstitial elements, and some heat treatments in the crystalline structure, microstructure and selected mechanical properties (Vickers microhardness, Young’s modulus and internal friction) of Ti-15Zr-xMo (5, 10, 15 and 20 wt%) alloys. The alloys exhibited dependence on the alloying elements and heat treatments, which resulted in different structural and microstructural changes. The mechanical properties were dependent on phase transformations induced by the compositions and heat treatments.

Abstract: Metallic biomaterials are used in various applications of the most important medical fields (orthopedic, dental and cardiovascular). The main metallic biomaterials are stainless steels, Co-based alloys and Ti-based alloys. Recently, titanium alloys are getting much attention for biomaterials because these types of materials have very good mechanical properties, good corrosion resistance and an excellent biocompatibility. The paper contains important information about titanium alloys used for biomedical applications, which are considered the most widely. It is very important to understand the microstructural evolution and property-microstructure relationship in implant alloys. In the present paper, authors present a short literature review on general aspects of promising biocompatible binary Ti-Mo alloys compared with CoCr and stainless steel alloys, as an alternative of the known metallic biomaterials. This alloys show superior mechanical compatibility and very good biocompatibility. The aim of this review is to highlight the mechanical properties for several types of biomaterials, their application in medical field, especially the Ti-Mo group.

Abstract: Titanium alloys present favorable properties to industry applications that depend on their composition and microstructure. Adding alloy elements and thermomechanical treatments can change the microstructure of titanium alloys. In this paper, Ti-15Zr alloys with different molybdenum quantities were prepared and hot-rolled, having been previously subjected to homogenizing heat treatment. The results showed that the microstructure of the alloys was sensible to heat treatment, in accordance with the theoretical prediction from the molecular orbital method.

Abstract: The internal friction of Ti-35.4Nb-0.05C (wt.%) was investigated using a dynamic mechanical analysis (DMA) Q800 from TA Instruments. It has been shown that a relaxational peak is observed in the water-quenched Ti-35.4-Nb-0.05C alloy on tanδ-temperature curve. The activation energy and pre-exponential factor of the peak are H_q=1.82±0.1 eV and τ_0q=1.7×10^-19±1 s, respectively. The activation energy value is a little larger than that of the water-quenched Ti-35.4-Nb alloy. The peak height is decreased compared with the water-quenched Ti-35.4-Nb alloy.

Abstract: Ti-Cu-Ni-Sn quaternary amorphous alloys of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7 composition were prepared by mechanical alloying in a planetary high-energy ballmill (AGO-2). The amorphization of all three alloys was found to set in after milling at 300rpm speed for 2h. A complete amorphization was observed for Ti50Cu32Ni15Sn3 and Ti50Cu25Ni20Sn5 after 30h and 20h of milling, respectively. Differential scanning calorimetry analyses revealed that the thermal stability increased in the order of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7.

Abstract: in the present study, amorphous ti50cu35-xni15snx (x=0~7) alloy powders were synthesized by mechanical alloying technique. the amorphization behavior of ti50cu28ni15sn7 alloy powders was examined in details by scanning electron microscopy, differential scanning calorimeter, x-ray diffraction, and synchrotron x-ray absorption spectroscopy. the results show that fully amorphous powders formed after 7 hours of milling. The thermal stability of the Ti50Cu35-xNi15Snx amorphous powders was investigated by differential scanning calorimeter. The amorphous Ti50Cu35Ni15 powders (i.e., x=0) exhibit no glass transition behavior. However, the amorphous Ti50Cu35-xNi15Snx (x=3~7) powders were found to exhibit a supercooled liquid region before crystallization. Amorphous Ti50Cu28Ni15Sn7 alloy powders exhibits a wide supercooled liquid region of 61 K.