Fabrication and Processing of Gamma Titanium Aluminides - A Review

2010 ◽  
Vol 638-642 ◽  
pp. 1281-1287 ◽  
Author(s):  
Yu Yong Chen ◽  
Yan Fei Chen ◽  
Fan Tao Kong ◽  
Shu Long Xiao
Keyword(s):  
Rapid Solidification ◽  
Investment Casting ◽  
Mechanical Milling ◽  
Titanium Aluminides ◽  
Research Work ◽  
Nanocrystalline Powders ◽  
Processing Route ◽  
Sheet Rolling ◽  
Tial Alloys ◽  
Institute Of Technology

The paper outlines some research work that has been conducted in Harbin Institute of Technology, on the fabrication of TiAl alloys. The review is presented with special emphasis on some different manufacturing routes of TiAl alloys, including investment casting, canned forging and sheet rolling, mechanical milling and rapid solidification. Investment casting has been developed to manufacture near-net shape TiAl blades. Also included are current development of canned forging and rolling for TiAl sheets. Then, TiAl nanocrystalline powders gained through low temperature and two steps mechanical milling were researched. And considerably refined TiAl alloys with Y additions were produced by rapid solidification and the microstructure evolution with Y addition was studied. Details of the processing route and microstructure related to different processing method will be presented.

Research on the Hot Precision Processing of TiAl Alloys

2009 ◽  
Vol 620-622 ◽  
pp. 407-412 ◽  
Author(s):  
Yu Yong Chen ◽  
Yan Fei Chen ◽  
Shu Long Xiao ◽  
Fan Tao Kong ◽  
Jing Tian ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Investment Casting ◽  
Industrial Application ◽  
Ingot Metallurgy ◽  
Sheet Rolling ◽  
Tial Alloys ◽  
Melting Technology ◽  
Operation Temperature ◽  
Recent Developments

γ-TiAl components due to their unique properties are on the verge of industrial application for increasing operation temperature and improving energy efficiency, especially in aerospace and automobile areas. This paper describes the recent developments of hot precision processing in ingot metallurgy technology including investment casting, canned forging and sheet rolling of TiAl alloys. Alloys development and the melting technology were discussed. Investment casting of TiAl alloys has been successfully developed to manufacture net-shape components. Research aimed at producing TiAl sheets through canned forging and rolling is introduced.

Robustness versus Performance Assessment for Different Gamma-TiAl Processing Routes

2011 ◽  
Vol 1295 ◽  
Author(s):  
Marc Thomas
Keyword(s):  
High Performance ◽  
Cost Effective ◽  
Processing Route ◽  
Transportation Industry ◽  
Tial Alloys ◽  
Alternative Processing ◽  
Aerospace Applications ◽  
Robust Processing ◽  
Processing Techniques ◽  
Robust Process

ABSTRACTOne of the main driving force for the development of advanced structural materials is weight saving especially in the transportation industry in order to reduce CO2 emission. The utilization of gamma aluminides, as good candidates for aerospace applications, is strongly related to the development of a cost-effective and robust processing route, as far as possible. It is well established that the processing route, i.e. cast, wrought or PM, has a dramatic effect on the microstructure and texture of gamma-TiAl alloys. Therefore, significant microstructural variations through post-heat treatments coupled with compositional modifications can only guarantee a proper balance of desired properties. However, a number of metallurgical factors during the processing steps can contribute to some scattering in properties. This review will highlight several critical process variables in terms of the resulting g-TiAl microstructures. Of primary importance is the as-cast texture which is difficult to control and may contribute to prefer some alternative processing routes to ensure a better repeatability in mechanical results. Some innovative processing techniques for controlling the structure will then be presented. The main point which will be discussed in this paper is whether an approach leading to a robust process would not be at the expense of the high performance of the structural material.

New Fe-Ni Based Metal-Metalloid Glassy Alloys Prepared by Mechanical Alloying and Rapid Solidification

1996 ◽  
Vol 455 ◽  
Author(s):  
J. J. Suñol ◽  
M. T. Clavaguera-Mora ◽  
N. Clavaguera ◽  
T. Pradell
Keyword(s):  
Mechanical Alloying ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Magnetic Interaction ◽  
Processing Route ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Glassy Alloys ◽  
Rapidly Solidified ◽  
Thermal Stability Of

ABSTRACTMechanical alloying and rapid solidification are two important routes to obtain glassy alloys. New Fe-Ni based metal-metalloid (P-Si) alloys prepared by these two different processing routes were studied by differential scanning calorimetry and transmission Mössbauer spectroscopy. Mechanical alloyed samples were prepared with elemental precursors, and different nominal compositions. Rapidly solidified alloys were obtained by melt-spinning. The structural analyses show that, independent of the composition, the materials obtained by mechanical alloying are not completely disordered whereas fully amorphous alloys were obtained by rapid solidification. Consequently, the thermal stability of mechanically alloyed samples is lower than that of the analogous material prepared by rapid solidification. The P/Si ratio controls the magnetic interaction of the glassy ribbons obtained by rapid solidification. The experimental results are discussed in terms of the degree of amorphization and crystallization versus processing route and P/Si ratio content.

The Use of In Situ Characterization Techniques for the Development of Intermetallic Titanium Aluminides

2014 ◽  
Vol 783-786 ◽  
pp. 2097-2102 ◽  
Author(s):  
Svea Mayer ◽  
Emanuel Schwaighofer ◽  
Martin Schloffer ◽  
Helmut Clemens
Keyword(s):  
Titanium Aluminides ◽  
Turbine Blades ◽  
Heat Treatments ◽  
Mechanical Processing ◽  
Tial Alloys ◽  
Solidification Processes ◽  
Consistent Picture ◽  
Aero Engines ◽  
Multi Phase

Urgent needs concerning energy efficiency and environmental politics require novel approaches to materials design. One recent example is thereby the implementation of light-weight intermetallic titanium aluminides as structural materials for the application in turbine blades of aero-engines as well as in turbocharger turbine wheels for the next generation of automotive engines. Each production process leads to specific microstructures which can be altered and optimized by thermo-mechanical processing and / or subsequent heat-treatments. To develop sound and sustainable processing routes, knowledge on solidification processes and phase transformation sequences in advanced TiAl alloys is fundamental. Therefore, in-situ diffraction techniques employing synchrotron radiation and neutrons were used for establishing phase fraction diagrams, investigating advanced heat-treatments as well as for optimizing thermo-mechanical processing. Summarizing all results a consistent picture regarding microstructure formation and its impact on mechanical properties in advanced multi-phase TiAl alloys can be given.

Microstructural Characterization of α2 + γ Titanium Aluminides

1997 ◽  
Vol 3 (S2) ◽  
pp. 701-702
Author(s):  
D. J. Larson ◽  
M. K. Miller
Keyword(s):  
Titanium Aluminides ◽  
Base Alloy ◽  
Significant Proportion ◽  
Weight Ratio ◽  
High Strength ◽  
Microstructural Characterization ◽  
Two Phase ◽  
Tial Alloys ◽  
Boron Doped

Two-phase α2+γ TiAl alloys with microalloying additions, Fig. 1, are of interest due to the high strength-to-weight ratio they can provide in automotive and aircraft applications. In boron-doped α2+γTiAl containing Cr, Nb, and W, the B levels were found to be significantly depleted below the nominal alloy content in both the α2 andγ phases. The boron solubilities in the γ and α2 phases were 0.011 ± 0.005 at. % B and 0.003 ± 0.005 at. % B, respectively in Ti-47% Al-2% Cr-1.8% Nb-0.2% W-0.15 % B that was aged for 2 h at 900°C (base alloy). The majority of the B was in a variety of borides including TiB, TiB2 and a Cr-enriched (Ti,Cr)2B precipitate. With the exception of the smaller (< 50 nm thick) Cr-enriched (Ti,Cr)2B precipitates, Fig. 2, most of the borides were larger than ∼100 nm. A significant proportion of the microalloying additions is in these borides, Table 1.

Elemental Segregation and O-Phase Formation in a Gamma-TiAl Alloy

2018 ◽  
Vol 941 ◽  
pp. 741-746 ◽  
Author(s):  
Heike Gabrisch ◽  
Tobias Krekeler ◽  
Uwe Lorenz ◽  
Marcus Willi Rackel ◽  
Martin Ritter ◽  
...  
Keyword(s):  
Tial Alloy ◽  
Titanium Aluminides ◽  
Orthorhombic Phase ◽  
Aircraft Engines ◽  
Duplex Microstructure ◽  
Two Phase ◽  
Chemical Homogeneity ◽  
Phase Form ◽  
Tial Alloys ◽  
O Phase

Titanium aluminides based on the L10 ordered g-phase are promising structural light-weight materials for applications in aircraft engines. Typical compositions for γ-TiAl alloys lie in the range Ti-(44-48)Al (at.-%). For high creep resistance, a two-phase microstructure based on lamellar (α2+γ)-colonies is desirable that may be tuned towards better ductility by introducing pure γ-grains (near lamellar or duplex microstructure).γ-TiAl alloys are often alloyed with niobium for increased oxidation resistance and improved mechanical properties. HEXRD and TEM studies of the alloy Ti-42Al-8.5Nb revealed that the orthorhombic O-phase forms during annealing at 500-650°C. This orthorhombic phase has been known in Nb-rich, Al-lean, α2-based Ti-aluminides since the late 1980ies (Nb> 12.5 at.-%, Al< 31 at.-%) but the finding in γ-based alloys is new.TEM imaging showed that the O-phase is located within α2 lamellae of lamellar (α2+γ)-colonies. O-phase domains and α2 phase form small columnar crystallites based in the α2/γ interface. The columnar crystallites grow parallel to the [0001] direction of the α2 phase and appear as facets when observed along this direction. The evolution of domains and facets with annealing time and the chemical homogeneity of the phases are investigated.The results of STEM imaging show that O-phase domains form during annealing at 550 °C for 8hours or 168 hours. After 168 hours of annealing Nb segregations are observed by EDX mapping within O-phase domains. In comparison, no segregation of niobium is detected after 8 hours of annealing.

Role of tool rotational speed on the tribological characteristics of magnesium based AZ61A/TiC composite developed via friction stir processing route

2020 ◽  
Vol 2 (101) ◽  
pp. 60-75
Author(s):  
P. Sagar ◽  
A. Handa
Keyword(s):  
Friction Stir Processing ◽  
Rotational Speed ◽  
Research Work ◽  
Wear Behaviour ◽  
Processing Route ◽  
Tool Rotational Speed ◽  
Tribological Behaviour ◽  
Friction Stir ◽  
Mechanism Research

Purpose: A new composite material was prepared and Different properties such as hardness and tribological behaviour of the fabricated metal matrix composite (MMC) was investigated and compared with the base AZ61A magnesium alloy. Design/methodology/approach: For the current research work, state-of-the-art technology, Friction stir processing (FSP) was performed to develop magnesium based AZ61A/TiC composite at optimized set of machine parameters. Findings: Increasing tool rotational speed ultimately leads in enhanced hardness, which further gives superior tribological properties as compared to base AZ61A alloy. Wear observations suggests a combination of abrasive and adhesive wear mechanism. Research limitations/implications: More microstructural and mechanical properties can be examined. Practical implications: The idea behind selecting AZ61A is mainly due to its increasing use in bicycle pedals and military equipment’s where at certain places it needs to encounter friction. In this current work, microhardness study and wear behaviour of AZ61A/TiC composite processed via FSP were examined. Originality/value: Paper is completely new and no work has been done till date considering this material and preparing composite with nanoparticles TiC.

Effect of Cast Geometries on Particle Dispersion in Metal Matrix Composites

2018 ◽  
Vol 877 ◽  
pp. 60-65 ◽  
Author(s):  
Vishal Mehta ◽  
Roma Patel ◽  
Mayur Sutaria
Keyword(s):  
Research Work ◽  
Stir Casting ◽  
Particle Dispersion ◽  
Processing Route ◽  
Metal Composite ◽  
Matrix Composites ◽  
Casting Technique ◽  
Discontinuous Reinforcement ◽  
Plate Geometry ◽  
Microstructural Examination

Metal composite materials are not being extensively used because of their complex processing, agglomeration and dispersion of particles in case of discontinuous reinforcement. Significant amount of research work has been carried to understand and improve primary processing of metal composites using liquid processing route. Most of the research revealed the fact that composites were cast either in plate geometry or geometry of crucible. Present work mainly focuses to examine effect of mold cavity geometries on dispersion of particles in solidifying composite slurries. Aluminium alloy composites using silicon carbide (SiC) particles were manufactured using stir casting technique. ‘T’ shape and plus shape geometries were cast in the present work. Critical velocity and solidification front velocity was analyzed to investigate effect of cast geometries on particle dispersion. Microstructural examination revealed that cast geometries have significant effect on dispersion of particles.

Production of SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powders via microwave processing route

2017 ◽  
Vol 46 (2) ◽  
pp. 85-91 ◽  
Author(s):  
Mohammadreza Johari ◽  
Masoud Rajabi ◽  
Vahid Mohammadi
Keyword(s):  
Sol Gel ◽  
Research Work ◽  
Precursor Solution ◽  
Heating System ◽  
Molar Ratio ◽  
Processing Route ◽  
X Ray Diffraction ◽  
Content Type ◽  
Microwave Assisted ◽  
Gel Processing

Purpose The present paper aims to synthesize SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powder using a combination of citrate – gel processing and microwave-assisted heating route. Design/methodology/approach Microwave-assisted citrate – gel processing of SrAl2O4:Eu2+, Dy3+ green-emitting phosphor nano-pigment powder has been carried out by varying the pH and the molar ratio of H3Cit/Al3+ + Sr2+ +Eu2++Dy3+ (f/o). X-ray diffraction analysis showed that the produced powders were nearly pure SrAl2O4 phase, in which the SrAl2O4 host phase has the maximum fraction of green-emitting monoclinic SrAl2O4 phase. Findings Spectrophotometer results revealed that two excitation peaks appeared at 238 and 339 nm and an emission peak at 515 nm. The crystallite size of the green-emitting phosphor nano-pigment powder was about 37 nm as determined by Scherrer’s formula. The best conditions for formation of monoclinic SrAl2O4 phase with high purity were achieved at pH of precursor solution equal to 7 and the molar ratio of f/o equal to 3. Originality/value The present research work for the first time (to the best of the authors’ knowledge) has used microwave and sol–gel combination techniques to produce green-emitting phosphor nano-pigment powder (without using any other heating system).

Rapidly Solidified Binary Tial Alloys

1986 ◽  
Vol 81 ◽  
Author(s):  
S. C. Huang ◽  
E. L. Hall ◽  
M. F. X. Gigliotti
Keyword(s):  
Electron Diffraction ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Grain Structure ◽  
Bending Tests ◽  
Tial Alloys ◽  
Compositional Effect ◽  
X Ray ◽  
Antiphase Domains ◽  
Rapidly Solidified

AbstractMelt spinning has been carried out on binary TiAl alloys at three Ti/Al ratios. Antiphase domains were observed in one ribbon specimen, but no significant disordering was induced by the rapid solidification as indicated by X-ray and electron diffraction analyses. Bending tests of both the ribbons and the consolidated counterparts showed a decrease in ductility with increasing Al concentration. This compositional effect can be correlated with the TiAl tetragonality (the c/a ratio) as well as the grain structure.

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