Oxidation Behavior of Intermetallic Titanium Aluminide Alloys

2012 ◽  
Vol 1516 ◽  
pp. 77-88 ◽  
Author(s):  
Michael Schütze ◽  
Simone Friedle
Keyword(s):  
Oxide Scale ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Life Time ◽  
Alloying Elements ◽  
Protective Oxide ◽  
High Temperature Alloys ◽  
Titanium Aluminide Alloys ◽  
Slow Growing

ABSTRACTAbove 750-800°C oxidation becomes a serious life time issue for the new group of intermetallic light-weight high temperature alloys based on titanium aluminides (TiAl). Fast growing titanium oxide competes with protective alumina as a surface scale in the oxidation reaction by which the formation of a slow-growing protective oxide scale is prevented. The key to the development of alloys with sufficient oxidation resistance is the understanding of the thermodynamic and kinetic situation during the oxidation process. The latter is influenced by the type of alloying elements, the Al- and Ti-activities in the alloy, the oxidation temperature and the environment (e.g. dry or humid air, etc.). This paper provides a comprehensive summary of the oxidation mechanisms and the parameters influencing oxide scale formation. Besides the role of metallic alloying elements, the halogen effect will also be discussed. The paper finishes with recent results concerning the prevention of oxidation-induced room temperature embrittlement of TiAl alloys.

The Dependence of Tensile Ductility on Investment Casting Parameters in Gamma Titanium Aluminides

1998 ◽  
Vol 552 ◽  
Author(s):  
R. Raban ◽  
L. L. ◽  
T. M.
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Tensile Ductility ◽  
Gamma Titanium Aluminide ◽  
Cooling Rates ◽  
Gamma Titanium ◽  
Investment Cast ◽  
Thermal Data ◽  
Titanium Aluminide Alloys ◽  
Simulation Package

ABSTRACTPlates of three gamma titanium aluminide alloys have been investment cast with a wide variety of casting conditions designed to influence cooling rates. These alloys include Ti-48Al-2Cr-2Nb, Ti- 47Al-2Cr-2Nb+0.5at%B and Ti-45Al-2Cr-2Nb+0.9at%B. Cooling rates have been estimated with the use of thermal data from casting experiments, along with the UES ProCAST simulation package. Variations in cooling rate significantly influenced the microstructure and tensile properties of all three alloys.

The role of (FeCrSi)2(MoNb)-type Laves phase on the formation of Mn-rich protective oxide scale on ferritic stainless steel

2018 ◽  
Vol 132 ◽  
pp. 214-222 ◽  
Author(s):  
Harri Ali-Löytty ◽  
Markku Hannula ◽  
Timo Juuti ◽  
Yuran Niu ◽  
Alexei A. Zakharov ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Oxide Scale ◽  
Ferritic Stainless Steel ◽  
Laves Phase ◽  
Protective Oxide ◽  
Protective Oxide Scale

scholarly journals A Review of Milling of Gamma Titanium Aluminides

2018 ◽  
Vol 3 (2) ◽  
pp. 1-9
Author(s):  
S. Castellanos ◽  
J. Lino Alves
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Chemical Reactivity ◽  
Cutting Tools ◽  
High Hardness ◽  
High Strength ◽  
Milling Process ◽  
Current Trends ◽  
Corrosive Environments ◽  
Titanium Aluminide Alloys

Intermetallic titanium aluminide alloys are used in the high technology engineering field with the goal of achieving weight reduction in different components, exposed to corrosive environments and high temperatures in aeronautical and automotive industries. Despite their attractive properties such as low density, high strength, high stiffness and good corrosion, creep and oxidation resistance, the machinability of titanium aluminide alloys is difficult due to its high hardness, chemical reactivity, and low ductility. This article reviews the state of the art regarding the machinability of titanium aluminide alloys and focuses on the analysis of the milling process, namely the process parameters, surface integrity and cutting tools. The influence of titanium aluminides properties on the machinability is also discussed presenting some current trends and further needed research.

scholarly journals Increased Wear and Oxidation Resistance of Titanium Aluminide Alloys by Laser Cladding

2011 ◽  
Vol 278 ◽  
pp. 515-520 ◽  
Author(s):  
Sörn Ocylok ◽  
Andreas Weisheit ◽  
Ingomar Kelbassa
Keyword(s):  
Laser Cladding ◽  
Titanium Aluminide ◽  
Thermal Stresses ◽  
Titanium Aluminides ◽  
State Of The Art ◽  
Base Material ◽  
Surface Oxidation ◽  
Tial Alloys ◽  
Gas Atmosphere ◽  
Titanium Aluminide Alloys

A process layout for laser cladding of layers on substrates of titanium aluminides using state-of-the-art and modified (additions of Si and TiB2) TiAl alloys is presented. The process involves a preheating of the samples to reduce thermal stresses and cladding in an inert gas atmosphere with an oxygen content lower than 30 ppm. These conditions lead to crack free layers and low surface oxidation. Microstructure and hardness of the layers are investigated. The abrasive wear resistance of the cladded layers in comparison to the base material is tested with promising results. Finally results of the oxidation behavior are shown and prove the increased performance of modified TiAl layers in comparison to the base material.

The Role Of Thermomechanical Energy In Diffusion Kinetics And Crystallinity Of Mechanically Alloyed Titanium Aluminides

1991 ◽  
Vol 238 ◽  
Author(s):  
Laura Dahl ◽  
Mark Shepler ◽  
Alexis S. Nash
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Weight Ratio ◽  
Heat Of Mixing ◽  
Light Weight ◽  
Diffusion Kinetics ◽  
Mechanically Alloyed ◽  
Fine Microstructure ◽  
Alloyed Titanium

ABSTRACTMechanical alloying, MA, is an amorphization technique which involves a solid state reaction below the crystallization temperature. This technique is capable of producing a more homogeneous and fine microstructure with improved mechanical properties. Amorphization of Titanium aluminide binary system, in the range of 45–65 at % Al is possible under optimized milling conditions since in this range the mixture has a large negative heat of mixing. This system is considered suitable for human implant applications for its light-weight, wear resistance, corrosion resistance, strength-to-weight ratio and biocompatibility.

Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

Zeit und gutes Leben

2020 ◽  
Vol 74 (4) ◽  
pp. 493-513
Author(s):  
Holmer Steinfath
Keyword(s):  
Internal Structure ◽  
Good Life ◽  
External Factor ◽  
Life Time ◽  
The Good Life ◽  
Adequate Understanding ◽  
Gutes Leben

Time is a neglected subject in recent, especially analytically minded reflections on the good life. The article highlights the fundamental role of time and temporality for an adequate understanding of the good life. Time functions both as an external factor with which we have to reckon in our practical deliberations and as an internal structure of living our lives. It is argued that striving for a good life also means striving for being in harmony with the time of one's life. The exploration of this idea allows to link analytical with phenomenological approaches to time and good life.

Mossbauer Study of the Role of Aluminum and Chromium in Nitrogen Implanted Iron

1991 ◽  
Vol 235 ◽  
Author(s):  
M. Kopcewicz ◽  
J. Jagielski ◽  
A. Turos ◽  
D. L. Williamson
Keyword(s):  
Thermal Stability ◽  
Ion Implantation ◽  
Metallic Iron ◽  
Conversion Electron ◽  
Alloying Elements ◽  
Mössbauer Study ◽  
Conversion Electron Mössbauer Spectroscopy ◽  
Conversion Electron Mossbauer Spectroscopy ◽  
Thermal Stability Of

ABSTRACTThe role of alloying elements such as Cr and Al in the formation and stability of the nitride phases formed due to N ion implantation into metallic iron was studied by conversion electron Mössbauer spectroscopy (CEMS). The thermal stability of nitride phases upon 1 h annealing was greatly increased as a result of co-implanting either Cr or Al with N as compared to pure α-Fe implanted only with N.

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