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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

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

Study of Milling and Sintering of Titanium Hydride Powders Aiming the Reduction of Oxygen as Interstitial Element

2012-10-02
2012-36-0232
Contamination of titanium by oxygen is inevitable during its processing by powder metallurgy (PM). When dissolved interstitially in the crystal lattice of titanium, oxygen exerts a great influence on strength and other mechanical properties. In this paper we investigated the effects of milling and sintering of titanium hydride powders on the levels of oxygen in sintered samples. To minimize contamination, milling was carried out under argon atmosphere and the manipulation of powders was performed inside a glove box. Samples were milled at two different particles sizes, isostatically pressed and sintered at 1000°C and 1200°C. The results indicated that the oxygen content in the final samples is mainly influenced by the level of oxygen in the starting powders and the particle size of these powders.
Technical Paper

Sintering of Titanium Alloys for Advanced Aerospace Systems

2005-11-22
2005-01-4180
Titanium alloys parts are ideally suited for advanced aerospace systems because of their unique combination of high specific strength at both room temperature and moderately elevated temperature, in addition to excellent corrosion resistance. Despite these features, use of titanium alloys in engines and airframes is limited by cost. The alloys processing by powder metallurgy (P/M) eases the obtainment of parts with complex geometry. In this work, results of the Ti-6Al-4V alloys production are presented. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 up to 1500 °C, in vacuum. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively.
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-35Zr-10Nb Alloy by Powder Metallurgy for Automotive Application

2004-11-16
2004-01-3353
The automotive industry has identified several automobile components that could be replaced with titanium alloy components, either through direct replacement in existing designs or, preferably, in new designs to fully exploit the unique properties of titanium. The alloy processing by powder metallurgy (M/P) eases the obtainment of parts with complex geometry and, probably, cheaper. In this work, results of the Ti-35Zr-10Nb alloy production are presented. This alloy due to its high wear, impact and corrosion resistance is a promising candidate for automotive applications. 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. Sintering behavior was studied by means of dilatometry. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively.
Technical Paper

Production of Ti-35Nb Alloy by Powder Metallurgy for Aerospace Application

2004-11-16
2004-01-3339
Titanium and its alloys provide high strength-to-weight ratios, good fatigue strength and increased corrosion resistance compared with others materials. Its acceptance in aerospace has been limited by costs considerations such as high cost of raw material, high buy-to-fly ratios and expensive machining operations. Significant cost reductions can be obtained by vacuum sintering and powder metallurgy (P/M) techniques by producing near net shapes and consequently minimizing material waste and machining time. The Ti 35Nb alloy exhibit a low modulus of elasticity. Stemming from the unique combination of high strength, low modulus of elasticity and low density, this alloy is intrinsically more resistant to shock and explosion damages than most other engineering materials. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 and 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

Production of Ti-10V-2Fe-3Al Alloy by Powder Metallurgy for Aerospace Applications

2006-11-21
2006-01-2851
The production of titanium alloys by powder metallurgy (P/M) techniques is effective and cheap method to obtain pieces and components due to its low cost in comparison with conventional techniques. The P/M aims to transform metallic powders, using pressure and heat, by means of a thermal treatment (sintering). Ti-10V-2Fe-3Al alloy was developed specifically for aerospace applications. Samples were produced by mixing of initial metallic powders followed by cold uniaxial and isostatic pressing with subsequent densification by sintering at 1200 °C and 1400° in vacuum. The alloy was characterized by means of scanning electron microscopy and Vickers indentation and density. The sample present high densities and homogeneous microstructure.
Technical Paper

Porosity Control in Ti-13Nb-13Zr Alloy Produced by Powder Metallurgy

2006-11-21
2006-01-2545
Titanium and titanium alloys are excellent candidates for aerospace and surgical implants applications owing to their high strength to weight ratio and good corrosion resistance. Among the titanium alloys recently developed, Ti-13Nb-13Zr is distinguished for presenting low modulus of elasticity, high mechanical resistance and superior biocompatibility, suitable for springs, bellows, surgical implants and aerospace parts with high resistance to shock and explosion damage. The alloys processing by powder metallurgy eases the obtainment of parts with complex geometry and near-net shape. In this work, results of the porosity control in the Ti-13Nb-13Zr alloy produced by powder metallurgy are presented. The samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the porosity level depends on the compaction pressures, sintering temperatures and holding times.
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

Microstructural investigation of Ti-48Al-2Cr-2Nb (at.%) obtained by powder metallurgy using hot uniaxial pressing

2008-10-07
2008-36-0264
The aim of this paper is to analyze the microstructural development in samples of Ti-48Al-2Cr-2Nb (at.%) alloys obtained by powder metallurgy (P/M). This alloy has potential applications when high operating temperatures are required, e. g. turbines, aerospace applications, automotive engines valves and turbocharger rotors. The elementary powders were mixed for 1 hour, cold uniaxially pressed at 60 MPa and sintered at 1100°C, for 1 hour, under vacuum. Then, the specimens were milled and submitted to a second stage that included cold isostatic pressing (400 MPa) with subsequent hot uniaxial pressing (20 MPa), between 900 up to 1200°C, for 2 hours, in argon atmosphere. The alloys were characterized by XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy) and Vickers microhardness measurements. The results indicated the viability of the route and the tendency of a lamellar microstructure in high sintering temperatures.
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

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

Development of titanium alloys production for high temperatures applications.

2010-10-06
2010-36-0170
Turbine blades for airplanes work in adverse conditions, under corrosive environment and high temperatures and pressure conditions. Ti-6Al-2Sn-4Zr-2Mo alloy was developed for high temperatures applications in aerospace area. In this work, Ti-6Al-2Sn-4Zr-2Mo alloy was obtained by powder metallurgy using titanium hydride powders. Samples were manufactured by blended elemental method from a sequence of uniaxial and cold isostatic pressing with subsequent densification by sintering among 800 up to 1400°C, in vacuum. The objective of this work is the analysis of microstructural evolution from the powders dissolution with the increase of the sintering temperature. The alloy was characterized by scanning electron microscopy, X-ray diffraction and Vickers microhardness measurement. Density was measured by Archimedes method.
Technical Paper

Development of Titanium Nitride Coatings in Titanium Alloys by Electron Beam Physical Vapor Deposition

2008-10-07
2008-36-0016
It is observed an increasing interest in using titanium nitride (TiN) coatings to improve the wear properties of Ti alloys. An important method is the Electron Beam Physical Vapor Deposition (EBPVD) that is a form of deposition in which a target anode is bombarded with an electron beam given off by a charged tungsten filament under high vacuum, producing a thin film in a substrate. In this work are presented results of the target and substrate production using Ti (C.P.), Ti-6Al-4V and Ti-13Nb-13Zr by powder metallurgy. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900 to 1500 °C, in vacuum. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the samples were sintered to high densities and presented homogeneous microstructure.
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

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

Developing of New Titanium Alloys by Powder Metallurgy for Aerospace Applications

2003-11-18
2003-01-3605
Titanium alloys parts are ideally suited for advanced aerospace systems because of their unique combination of high specific strength at both room temperature and moderately elevated temperature, in addition to excellent general corrosion resistance. Despite these attractive features, use of titanium alloys in engines and airframes is limited by cost. The alloys processing by powder metallurgy eases the obtainment of parts with complex geometry and probably, cheaper. In this work, results of the Ti-6A1-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys production are presented. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering at 1500 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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