Microstructure and Processing Ability of β-Solidifying TNM-Based γ-TiAl Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 235-240 ◽  
Author(s):  
V.M. Imayev ◽  
Renat M. Imayev ◽  
Timur G. Khismatullin ◽  
T. Oleneva ◽  
Volker Gühter ◽  
...  
Keyword(s):  
Lamellar Structure ◽  
Room Temperature ◽  
Critical Issue ◽  
Hot Workability ◽  
Tial Alloys ◽  
Room Temperature Ductility ◽  
Processing Ability ◽  
Cast Condition

Microstructure and hot workability have been considered for a number of -TiAl alloys including -solidifying TNM alloys. All TNM alloys under study showed improved hot workability in cast condition. As was shown for the Ti-45Al-5Nb-1Mo-0.2B alloy, a critical issue of TNM alloys is room temperature ductility in the conditions with lamellar structure.

scholarly journals The Microstructural Evolution, Tensile Properties, and Phase Hardness of a TiAl Alloy with a High Content of the β Phase

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2757 ◽  
Author(s):  
Ning Cui ◽  
Qianqian Wu ◽  
Zhiyuan Yan ◽  
Haitao Zhou ◽  
Xiaopeng Wang
Keyword(s):  
Tensile Properties ◽  
Room Temperature ◽  
Tial Alloy ◽  
Microstructural Analysis ◽  
Phase Content ◽  
Tial Alloys ◽  
Β Phase ◽  
Room Temperature Ductility ◽  
One Step ◽  
Equiaxed Grains

In this paper, the microstructure, deformability, tensile properties, and phase hardness of the Ti–43Al–2Cr–0.7Mo–0.1Y alloy with a high β phase content were investigated. Microstructural analysis showed that the β phase precipitated not only at the colony boundaries but also inside the lamellae due to its high content. A high-quality forging stock was prepared through one-step noncanned forging. The total deformation reached above 80%, suggesting that the alloy has good hot deformability compared to other TiAl alloys. The deformed microstructure was composed of fine and equiaxed grains due to dynamic recrystallization. The high β phase content was shown to contribute to the decomposition of the initial coarse lamellae. Tensile testing showed that the alloy has good room-temperature ductility, even if the β phase content reaches above 20%. This is inconsistent with a previous study that showed that a large amount of the hard β phase is detrimental to the room-temperature ductility of TiAl alloys. Nanoindentation testing showed that the hardness of the β phase in the current alloy is about 6.3 GPa, which is much lower than that in the Nb-containing TiAl alloys. Low hardness benefits the compatible deformation among various phases, which could be the main reason for the alloy’s good room-temperature ductility. Additionally, the influence of various β stabilizers on the hardness of the β phase was also studied. The β phase containing Nb had the highest hardness, whereas the β phase containing Cr had the lowest hardness.

scholarly journals Deformation and Fracture of TiAl Alloys with a Coarsely Spaced Lamellar Structure on Compression Test at Room Temperature

2001 ◽  
Vol 65 (11) ◽  
pp. 1029-1037 ◽  
Author(s):  
Katsuhiko Nonaka ◽  
Takeshi Kawabata ◽  
Hideo Nakajima ◽  
Kazuo Tanosaki ◽  
Jun-ichi Echigoya
Keyword(s):  
Compression Test ◽  
Lamellar Structure ◽  
Room Temperature ◽  
Tial Alloys ◽  
Deformation And Fracture

The Effect of Grain Refinement on the Room-Temperature Ductility of As-Cast Fe3Al-Based Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
S. Viswanathan ◽  
V. K. Andleigh ◽  
C. G. McKamey
Keyword(s):  
Grain Refinement ◽  
Room Temperature ◽  
Maximum Stress ◽  
Cast Alloy ◽  
Room Temperature Ductility ◽  
Bend Tests ◽  
Point Bend ◽  
Carbon Additions ◽  
Cast Condition ◽  
Strength And Ductility

AbstractFe3Al-based alloys exhibit poor room temperature ductility in the as-cast condition. In this study, the effect of grain refinement of the as-cast alloy on room-temperature ductility was investigated. Small melts of Fe-28 at. % Al-5 at. % Cr were inoculated with various alloying additions and cast into a 50- × 30- × 30-mm graphite mold. The resulting ingots were examined metallographically for evidence of grain refinement, and three-point bend tests were conducted on samples to assess the effect on room-temperature ductility. Ductility was assumed to correlate with the strain corresponding to the maximum stress obtained in the bend test. The results showed that titanium was extremely effective in grain refinement, although it severely embrittled the alloy in contents exceeding 1%. Boron additions strengthened the alloy significantly, while carbon additions reduced both the strength and ductility. The best ductility was found in an alloy containing titanium, boron, and carbon.

Ultrafine Fully-Lamellar Structures in Two-Phase γ-TiAl Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
P. J. Maziasz ◽  
C. T. Liu
Keyword(s):  
Room Temperature ◽  
Interlamellar Spacing ◽  
Hot Extrusion ◽  
Processing Parameters ◽  
High Temperature Strength ◽  
Two Phase ◽  
Tial Alloys ◽  
Room Temperature Ductility ◽  
Heat Treated ◽  
Fully Lamellar

ABSTRACTSpecial ultrafine fully-lamellar microstructures have been found recently in γ-TiAl alloys with 46–48 at.% Al, when they are processed or heat-treated above the α-transus temperature (Tα). Hot-extrusion above Tα also produces a refined colony or grain size. Refined-colony/ultrafine-lamellar (RC/UL) microstructures produce an excellent combination of room-temperature ductility and high-temperature strength in Ti-47Al-2Cr-2Nb (at.%) alloys. UL structures generally have an average interlamellar spacing of 100–200 nm, and have regularly alternating γ and α2 lamellea, such that they are dominated by γ/α2 interfaces with relatively few γ/γ twin boundaries. The focus of this study is how variations in processing parameters or alloy composition affect formation of the UL structure, particularly the α2 component.

Microstructure Design for Enhancement of Room-temperature Ductility in Multi-component TiAl Alloys

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1523-1529 ◽  
Author(s):  
Ryosuke Yamagata ◽  
Yotaro Okada ◽  
Hideki Wakabayashi ◽  
Hirotoyo Nakashima ◽  
Masao Takeyama
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Significant Contribution ◽  
Volume Fraction ◽  
Microstructure Design ◽  
Tial Alloys ◽  
Volume Fractions ◽  
Β Phase ◽  
Room Temperature Ductility

AbstractEffects of microstructure constituents of α2-Ti3Al/γ-TiAl lamellae, β-Ti grains and γ grains, with various volume fractions on room-temperature ductility of γ-TiAl based alloys have been studied. The ductility of the alloys containing β phase of about 20% in volume increases to more than 1% as the volume fraction of γ phase increases to 80%. However, γ single phase alloys show very limited ductility of less than 0.2%. The present results, thus, confirmed the significant contribution of β phase to enhancement of the room-temperature ductility in multi-component TiAl alloys.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

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