Evolution of hot rolling texture in β (B2)-phase of a two-phase (O+B2) titanium–aluminide alloy

2008 ◽  
Vol 483-484 ◽  
pp. 551-554 ◽  
Author(s):  
S.R. Dey ◽  
Satyam Suwas ◽  
J.-J. Fundenberger ◽  
J.X. Zou ◽  
T. Grosdidier ◽  
...  
Keyword(s):  
Hot Rolling ◽  
Titanium Aluminide ◽  
Rolling Texture ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
B2 Phase

Stress Driven Phase Transformations and Recrystallization Processes in Two-Phase Titanium Aluminide Alloys

2000 ◽  
Vol 652 ◽  
Author(s):  
Fritz Appel ◽  
Michael Oehring
Keyword(s):  
Phase Transformation ◽  
Titanium Aluminide ◽  
Electron Microscope Study ◽  
Phase Boundaries ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Lower Solubility ◽  
Term Creep ◽  
Titanium Aluminide Alloys

ABSTRACTThe paper presents an electron microscope study of phase transformation and recrystallization in an intermetallic α2(Ti3Al) + γ(TiAl) titanium aluminide alloy, after long-term creep. The mechanisms are closely related to the atomic structure of the α2/γ phase boundaries and are probably driven by a non-equilibrium of the phase composition leading to the dissolution of the α2 phase. The α2 /γ transformation is accompanied by the formation of precipitates, because the γ(TiAl)phase has a significantly lower solubility for interstitial impurities than the α2(Ti3Al) phase.

Microstructure and interfaces in TiB2/Ti-46Al-3Cr Alloy Composites

1995 ◽  
Vol 410 ◽  
Author(s):  
Weimin Si ◽  
Michael Dudley ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Electron Microscopy ◽  
Titanium Aluminide ◽  
Analytical Electron Microscopy ◽  
Lattice Misfit ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Resolution Electron ◽  
Crystallographic Orientation Relationship

ABSTRACTA ternary titanium aluminide alloy, Ti-46Al-3Cr (at%), was discontinuously reinforced with 5 vol% titanium diboride (TiB2), by an in-situ synthesis technique, resulting in a two phase γ(TiAl) (mainly) and α2(Ti3Al) matrix with randomly dispersed TiB2 particle. Interfaces of TiB2-TiAl were investigated by Analytical Electron Microscopy (AEM) and High Resolution Electron Microscopy (HREM). No consistent crystallographic orientation relationship was observed between TiB2 particle and TiAl matrix, and there was no evidence of alloying elements (such as Cr) segregation or interphase formation at the TiB2-TiAl interface. HREM results indicated that no semi-coherent interface between TiB2 and TiAl has been observed. There existed a thin amorphous layer (0.5 to 1.3 nm) at the TiB2-TiAl interface, which may accommodate the large lattice misfit across the interface and enhance the interfacial bonding.

Creep Deformation of a Fully Lamellar Gamma Based Titanium Aluminide Alloy

1996 ◽  
Vol 460 ◽  
Author(s):  
F. Herrouin ◽  
P. Bowen ◽  
I. P. Jones
Keyword(s):  
Gas Turbine ◽  
Creep Deformation ◽  
Titanium Aluminide ◽  
Creep Resistance ◽  
Tial Alloy ◽  
Operating Conditions ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Aero Engine ◽  
Fully Lamellar

ABSTRACTA complex two phase γ-TiAl alloy, Ti-47Al-lCr-1Mn-2Ta-0.2Si (at.%) in a fully lamellar condition, has been creep tested at a stress of 200MPa and a temperature of 700°C. This simulates the in-service operating conditions for several potential gas turbine aero engine applications where creep resistance is a design limiting material property. The results have indicate that reduction in lamellae thickness and avoidance of feathery type microstructures contribute to improved creep resistance.

Solution and Precipitation Hardening in Carbon-Doped Two-Phase γ-Titanium Aluminides

1996 ◽  
Vol 460 ◽  
Author(s):  
F. Appel ◽  
U. Christoph ◽  
R. Wagner
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Precipitation Hardening ◽  
Titanium Aluminides ◽  
Activation Parameters ◽  
High Temperature Strength ◽  
Thermal Treatments ◽  
Two Phase ◽  
Carbon Doped ◽  
Titanium Aluminide Alloy

ABSTRACTA two-phase titanium aluminide alloy was systematically doped with carbon to improve its high temperature strength. Solid solutions and precipitates of carbon were formed by different thermal treatments. A fine dispersion of perovskite precipitates was found to be very effective for improving the high temperature strength and creep resistance of the material. The strengthening mechanisms were characterized by flow stresses and activation parameters. The investigations were accompanied by electron microscope observation of the defect structure which was generated during deformation. Special attention was paid on the interaction mechanisms of perfect and twinning dislocations with the carbide precipitates.

Experimental and Numerical Investigation of Texture Development during Hot Rolling of Magnesium Alloy AZ31

2007 ◽  
Vol 539-543 ◽  
pp. 3448-3453 ◽  
Author(s):  
C. Schmidt ◽  
Rudolf Kawalla ◽  
Tom Walde ◽  
Hermann Riedel ◽  
A. Prakash ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Hot Rolling ◽  
Rolling Texture ◽  
Rolling Process ◽  
Model Parameters ◽  
Compression Tests ◽  
Basal Texture ◽  
Alloy Az31 ◽  
Magnesium Alloy Az31 ◽  
Softening Behavior

Due to the deformation mechanisms and the typical basal texture rolled magnesium sheets show a significant asymmetry of flow stress in tension and compression. In order to avoid this undesired behavior it is necessary to achieve non-basal texture during rolling, or at least, to reduce the intensity of the basal texture component. The reduction of the anisotropy caused by the basal texture is very important for subsequent forming processes. This project aims at optimizing the hot rolling process with special consideration of texture effects. The development of the model is carried out in close cooperation with the experimental work on magnesium alloy AZ31 .The experimental results are required for the determination of model parameters and for the verification of the model. Deformation-induced texture is described by the visco-plastic self-consistent (VPSC) model of Lebensohn and Tomé. The combination of deformation and recrystallization texture models is applied to hot compression tests on AZ31, and it is found, that the model describes the observed texture and hardening/softening behavior well. In some cases rotation recrystallization occurs in AZ31 which appears to be a possibility to reduce the undesired basal rolling texture.

Localized Oxidation Near Cracks and Lamellar Boundaries in a Gamma Titanium Aluminide Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
J. Kameda ◽  
C. R. Gold ◽  
E. S. Lee ◽  
T. E. Bloomer ◽  
M. Yamaguchi
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Lamellar Structure ◽  
Oxidation Behavior ◽  
Stress Axis ◽  
Surface Cracks ◽  
Gamma Titanium Aluminide ◽  
Titanium Aluminide Alloy ◽  
Scanning Auger Microprobe ◽  
Local Oxidation

AbstractSmall punch (SP) tests on single grained titanium aluminide (Ti-48 at.%Al) specimens with 12° and 80° lamellar orientations with respect to the tensile stress axis were conducted at 1123 K in air. Brittle cracks readily extended through the thickness in the 80° lamellar structure. In a SP specimen with the 12° lamellar structure load-interrupted at the strain of 0.43%, surface cracks with the depth of 15–25 μm were formed along lamellar boundaries. Local oxidation behavior on partly sputtered surfaces in the load-interrupted 12° lamellar specimen was examined using scanning Auger microprobe (SAM). Oxygen enriched regions were observed near cracks and some lamellar layers. The mechanisms of high temperature oxygen-induced cracking are discussed in terms of the local oxidation near cracks and lamellar boundaries.

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