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Technical Paper

Development of Production Techniques for Aerospace Titanium Alloys

2013-10-07
2013-36-0370
Titanium alloys parts are ideally suited for advanced aerospace systems because of their unique combination of high specific strength and superior resistance to many corrosive environments, in addition to excellent composite compatibility. Despite these features, use of titanium alloys in engines and airframes is limited by cost. Therefore, the improvement of processing techniques for titanium alloys production became a trend of the modern metallurgic technology. This work presents results of the microstructural development of Ti-6Al-2Sn-4Zr-2Mo alloy produced by arc melting and powder metallurgy processes. This alloy has important applications in aerospace area, in sections exposed to high temperatures. Samples of this alloy were characterized by SEM (scanning electron microscopy), XRD (X-ray diffraction), Vickers microhardness measurements and density.
Technical Paper

Development of Techniques for Gamma Ti-Al Production

2013-10-07
2013-36-0392
Gamma Ti-Al (γ Ti-Al) has excellent mechanical properties and oxidation/corrosion resistance at elevated temperatures (above 700°C), which makes it a possible replacement for traditional Ni based superalloy components in aircraft turbine engines and in orbital platform vehicles. The alloy design and efficient routes of TiAl processing are important technological challenges. In this work, samples of Ti-48Al-2Cr-2Nb (at.%) were produced by powder metallurgy processes. Using powder metallurgy, samples were prepared from elemental and pre-alloyed powders mixed for 2 h, followed by cold uniaxial and isostatic pressing and sintered between 1100°C up to 1400°C, for 1 h, under vacuum. After metallographic preparation, samples were characterized by SEM (Scanning Electron Microscopy), X-ray diffraction (XRD), density analyses and Vickers microhardness measurements.
Technical Paper

Production of Ti-Zr Alloy by Powder Metallurgy

2013-10-07
2013-36-0388
The powder metallurgy allows titanium alloy production with savings of energy and time with higher microstructural homogeneity than those obtained by conventional processes. The processing of titanium alloys is increasing in industry, since these alloys presenting superior mechanical properties than commercially pure titanium. Ti-Zr alloys with zirconium contents ranging from 10 to 40 wt% have been investigated by melting process along the last years. In these alloys were reported characteristics as excellent corrosion resistance and high biocompatibility. In this work Ti-40Zr was produced by powder metallurgy in order to produce parts with complex geometry with high microstructural homogeneity to be applied in areas such as the space industry and surgical implants. Samples were produced by mixing of initial hydrided powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 800-1600 °C, in vacuum.
Technical Paper

Production of Ti-22Nb-6Zr Shape Memory Alloy by Powder Metallurgy

2012-10-02
2012-36-0467
Shape Memory Alloys (SMA) are novel materials which have the ability to return to a predetermined shape when heated. SMA are useful as actuators which are materials that change shape, stiffness, position, natural frequency, and other mechanical characteristics in response to temperature or electromagnetic fields. Applications include engines in cars and airplanes, electrical generators and surgical implants that make use of the mechanical energy resulting from the shape transformations. Powder metallurgy allows the SMA production with savings of energy and time and with higher microstructural homogeneity than those obtained by conventional processes. In this work a new nickel-free titanium alloy Ti-22Nb-6Zr (%at) was produced in order to expand the application field of SMA. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 800-1600°C, in vacuum.
Technical Paper

Ti/TiN Multilayer Coatings on Titanium Alloys

2012-10-02
2012-36-0236
Titanium alloys have been widely used in manufacturing of fans, compressor disks, and blades of advanced aircraft engines. However, titanium alloys are very sensitive to fretting fatigue damage, which may affect the safe reliability of the aircraft engine compressor. The multilayer coatings seem to be the most promising coating concept due to many requirements (e.g. multifunctional character, moderate residual stresses, good adherence to metallic substrates, proper hardness to toughness ratio and low friction coefficients) for titanium alloys exposed to complex wear conditions. This work aims the development of techniques for production of Ti/TiN multilayer coatings by Electron Beam Physical Vapor Deposition (EB-PVD) in order to define the influence of the number and thickness of the layers in the surface hardness of Ti-13Nb-13Zr alloy produced by powder metallurgy (P/M) from elemental hydrides.
Technical Paper

Microstructural Study of Ti-6Al-4V Produced with TiH2 Powder

2012-10-02
2012-36-0197
In the aerospace industry, 80-90% of the titanium used in airframes has been from Ti-6Al-4V. This alloy is used throughout the section of an aircraft - fuselage, nacelles, landing gear, wing and empennage. In gas turbine engines Ti-6Al-4V is used in static and rotating components. Castings are used for the manufacture of more complex static components; forgings are typically used for moving parts. Conventional methods for obtaining titanium alloys require special conditions of controlled atmosphere that culminates in a high production cost. In this paper it was investigated the peculiarities of the typical microstructure of Ti-6Al-4V produced by powder metallurgy using TiH₂ powder. Samples were produced from the initial mixture of Al, V and TiH₂ powders, followed by cold uniaxial and isostatic pressing with subsequent densification by sintering in temperatures between 800-1400°C, in vacuum.
Technical Paper

Multilayer Coatings on Titanium alloys

2011-10-04
2011-36-0038
The production of multilayer allows the insertion of several interfaces over a substrate. The technological applications of the multilayer coatings involve optical, electromagnetism and wear areas. This paper aims the development of techniques for production of multilayer coatings with titanium nitride (TiN) and zirconium nitride (ZrN) obtained by Physical Vapor Deposition (PVD) from the use of an electron beam furnace. Moreover, the work includes the production of substrates (samples of Ti-35Nb-7Zr-5Ta) obtained by powder metallurgy from elemental hydrides and targets of Ti and Zr. The substrates were produced by mixing the elemental powders with subsequent steps of cold pressing and sintering at 1400°C in vacuum. The coatings were characterized by optical microscope, scanning electron microscope (SEM), chemical analysis via energy dispersive spectrometry (EDS) and Vickers indentation.
Technical Paper

Gamma Ti-Al Alloy Production for Aerospace Applications

2011-10-04
2011-36-0042
Gamma-TiAl alloys are potential replacements for nickel alloys and conventional titanium alloys in hot sections of turbine engines, as well as in orbital platform vehicles. The combination of high specific stiffness and good oxidation resistance at intermediate temperatures can provide significant weight savings. However, they have a limited plasticity at room temperature and the tendency to brittle fracture. Powder metallurgy is a near net shape process that allows the parts production with complex geometry at low costs. An improved plasticity of the Ti-Al alloys is received by adding alloying elements and by microstructure modification. An alloy of two-phase structure Ti-48Al-2Cr-2Nb (at.%) was investigated using the blended elemental technique. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 1100-1400°C, in vacuum.
Technical Paper

Techniques for Ti-6Al-4V Production by Powder Metallurgy

2011-10-04
2011-36-0040
Titanium alloys parts are ideally suited for advanced systems because of their unique combination of high specific and corrosion resistance. Ti-6Al-4V is the most important titanium alloy and its application ranges from aerospace to surgical implants. Despite these attractive features, use of titanium alloys is limited by cost. The alloys processing by powder metallurgy ease the obtainment of parts with complex geometry and probably, cheaper. In this work, new routes of Ti-6Al-4V production by powder metallurgy are investigated. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900-1400°C, in vacuum. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Density was measured by Archimedes method.
Technical Paper

Densification of titanium alloys obtained by powder metallurgy

2010-10-06
2010-36-0235
Titanium alloys parts are ideally suited for advanced aerospace systems, chemical and naval applications and surgical implants because of its high strength-to-weight ratio, high resistance to many corrosive environments, and can be used over a wide range of temperatures. Powder metallurgy of titanium and Ti-based alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. In this work, results of the densification of Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys after cold and isostatic pressing with subsequent densification by sintering between 900-1400°C using hydride titanium powders are presented. The samples were characterized by X-ray diffraction, scanning electron microscopy, Vickers indentation and density measurements.
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