Microstructural Characterization of Silicon Added Titanium Aluminide

2010 ◽  
Vol 442 ◽  
pp. 74-80 ◽  
Author(s):  
Aamer Nusair Khan
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Silicon Oxide ◽  
Microstructural Characterization ◽  
Alumina Scale ◽  
Analysis Techniques ◽  
Automotive Engines ◽  
The Past ◽  
Oxidation Properties

Titanium aluminides intermetallic compounds have received great attention during the past decade, since they have the potential, in aircraft and automotive engines, to replace the high density Ni-base superalloys However, these intermetallics possess poor oxidation properties at high temperatures. Previous studies showed that protective alumina scale formation on γ-TiAl can be obtained by small additions (around 2 at.%) of Ag. In the present study, a number of cast Ti–Al–Si alloys were investigated in relation to transient oxide formation in air at 1300°C. After various oxidation times the oxide composition, microstructure and morphology were studied by combining a number of analysis techniques. The TiAl–Si alloys appear to form Al Ti and Si oxides. However, the formation of silicon oxide at the interface of base metal and scale slows down the oxidation rate significantly.

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.

Qualification of an Investment Casting Process for Production of Titanium Aluminide Components for Aerospace and Automotive Applications

2010 ◽  
Vol 638-642 ◽  
pp. 1275-1280 ◽  
Author(s):  
Julio Aguilar ◽  
Ulrike Hecht ◽  
Andre Schievenbusch
Keyword(s):  
Investment Casting ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Centrifugal Casting ◽  
Casting Process ◽  
The Past ◽  
Production Route ◽  
Automotive Parts ◽  
Near Net Shape ◽  
Cluster Design

Over the past years significant efforts were dedicated to developing production processes for aerospace and automotive parts from light weight titanium aluminides. Considerable progress was achieved worldwide in the field of near net shape casting. Access has developed an own production route, based on centrifugal investment casting. Various components from TiAl-based alloys, including turbocharger wheels and stator vanes were successfully cast and supplied for engine tests. A newly developed automated centrifugal casting line was recently taken into operation. This presentation will describe our activities that aimed to qualify the casting line for series production of turbocharger wheels: apart from basic issues of casting cluster design, process control and quality inspection we will discuss the casting process from the perspective of its techno-economic characteristics

Microstructural Characterization of Crystalline and Quasicrystalline Phases in AlCuFe Alloys.

1997 ◽  
Vol 3 (S2) ◽  
pp. 705-706
Author(s):  
G. Rosas ◽  
J. Reyes-Gasga ◽  
R. Pérez
Keyword(s):  
Structural Characteristics ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Icosahedral Phase ◽  
Ternary Alloys ◽  
Casting Method ◽  
Casting Technique ◽  
The Past ◽  
Wheel Casting

Recent interest in the literature on ternary compounds of the AlCuFe type has been prompted by the discovery of stable quasicrystalline phases in these type of alloys (1) . Therefore, different investigationes have been carried out in the past, related with the structural characteristics and also the mechanical properties of these compounds (2) . It is interesting to point out that very few studies have been carried out on the structural characteristics of the phases which commonly coexist with the icosahedral phase in this ternary alloy (3) . In this investigation an assessment of the chemical and structural properties of the phases obtained in alloys of AlCuFe is carried out.Ternary alloys with approximately 20 different compositions have been prepared. The compositional ranges were: Al(60-65%at), Cu(20-25%at) and Fe(10-15%at). The preparation of the alloys used two different casting process; a gravity chill casting technique and also the spin wheel casting method. These casting techniques were able to provide different cooling velocities in the final ingots or metallic strips.

Chemical Synthesis and Characterization of Nanostructured Titanium Aluminide

1994 ◽  
Vol 351 ◽  
Author(s):  
S.T. Schwab ◽  
P.P. Paul ◽  
Y-M. Pan
Keyword(s):  
Heat Treatment ◽  
Chemical Analysis ◽  
Chemical Synthesis ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Synthesis And Characterization ◽  
Nanostructured Titanium ◽  
Nanosize Particles

ABSTRACTAlthough plagued by a lack of ductility, titanium aluminides are among the most promising intermetallics under development. Significant improvements in ductility may be obtained from nanostructured intermetallics. Nanosize particles of TiAl3 have been prepared by heat-treatment of chemically synthesized precursor (compound 1). Nanosized TiAl3 has been characterized by chemical analysis, XRD, EDS, NMR, and HREM.

scholarly journals Microstructural characterization of twin-roll cast gamma titanium aluminide sheets.

1991 ◽  
Vol 31 (3) ◽  
pp. 289-297 ◽  
Author(s):  
Munetsugu Matsuo ◽  
Toshihiro Hanamura ◽  
Masao Kimura ◽  
Naoya Masahashi ◽  
Toshiaki Mizoguchi ◽  
...  
Keyword(s):  
Titanium Aluminide ◽  
Microstructural Characterization ◽  
Gamma Titanium Aluminide ◽  
Gamma Titanium ◽  
Twin Roll Cast ◽  
Twin Roll

High-resolution Electron Microscopy characterization of chemically derived titanium aluminide nanomaterials

1994 ◽  
Vol 52 ◽  
pp. 756-757
Author(s):  
Y.-M. Pan ◽  
P. P. Paul ◽  
S. T. Schwab
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
High Resolution Electron Microscopy ◽  
Full Potential ◽  
Resolution Electron ◽  
Microscopy Characterization ◽  
Hexane Solution

Titanium aluminides are a class of intermetallics whose application to a variety of advanced structures may yield substantial improvements in system performance. Before titanium aluminides can realize their full potential, a number of deficiencies such as lack of ductility must be overcome through improved processing. Difficulties inherent in traditional methods have prompted the development of the ultrastructure approach to materials processing. Chemical processing has best potential for ultrastructure control because articles are constructed from atomic level up. The availability of nanostructured materials may be essential to the development of intermetallics with acceptable levels of ductility. The focus of this work is to use high resolution electron microscopy (HREM) techniques to characterize the structure and chemistry of the chemically-derived, nanocrystalline intermetallic powders that have potential to enable ultrastructure processing of advanced intermetallics and alloys.In an attempt to produce salt-free TiAl3, a dilute hexane solution of Ti[N(SiMe3)2]3 was combined with an excess of (AIH3) at room temperature to yield a very fine, steel-gray powder.

Microstructural characterization of Cu-Sn-Ni Solder in microelectronic packaging

1996 ◽  
Vol 54 ◽  
pp. 508-509
Author(s):  
J. G. Duh ◽  
C. C. Young ◽  
C. H. Cheng
Keyword(s):  
Solder Joints ◽  
Environmental Concern ◽  
Microstructural Characterization ◽  
Microelectronic Packaging ◽  
The Past ◽  
Ni Alloys ◽  
Metallized Layer ◽  
Free Replacement ◽  
Growth Evolution

Microelectronic packaging has experienced exciting growth in the past years, and solder joints plays important roles in the reliability of package system. Lead-tin (Pb-Sn) alloys are the most prominent solders for the interconnection and packaging of modern electionic components and devices. However, there are environmental concern on the toxicity of Pb. These concerns have inspired a great deal of research to study the feasibility of lead-free replacement alloys. It is known that the presence of intermetallic is often an indication of good wetting in solder joints. Nevertheless, excessive intermetallic growth may be detrimental to joint reliablity. The purpose of this study is to investigate the growth evolution between unleaded Cu-Sn-Ni alloys and metallized layer. These results will help to characterize the effect of aging on the microstructural and mechanical properties of solder / metallized layer / substrate systems.

Impurity-controlled contrast in secondary-electron images of reaction-bonded silicon carbide

1990 ◽  
Vol 48 (4) ◽  
pp. 888-889
Author(s):  
R.A. Youngman
Keyword(s):  
Secondary Electron ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
The Past ◽  
Contrast Mechanism ◽  
Backscattered Electron ◽  
In Situ Formation ◽  
Secondary Ion

Reaction-bonded SiC is formed by the high temperature (>2100°C) heat treatment of a mixture of alpha-SiC powder and organic binders in the presence of elemental Si. The bonding occurs by the in-situ formation of beta-SiC from the reaction of the pyrolyzed binder and the Si. Substantial microstructural characterization of these materials has been carried out in the past. A particular feature of these analyses is the so-called trace-impurity-controlled contrast of secondary electron (SE) images of uncoated specimens. This report describes further attempts to elucidate the origin of this contrast mechanism.Samples of reaction-bonded SiC (Hexoloy KT, The Carborundum Co.) were prepared for multiple-technique analysis. This was accomplished by preparing an optical thin section for reflected and transmitted optical microscopy. Regions of interest were diamond-scribed on the optical microscope (Leitz, Orthoplan) and then SE and backscattered electron (BE) microscopy (CamScan, Series IV) of the same areas (both coated and uncoated with evaporated carbon) was conducted. Finally, the same areas were imaged in a secondary ion mass spectrometer (SIMS) (Cameca, IMS3F) to detect trace and major impurity levels.

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