Fabrication of Ti-43Al-5V-4Nb Intermetallic Compounds by Forging Using the Blended Elemental Powders

2011 ◽  
Vol 308-310 ◽  
pp. 796-799 ◽  
Author(s):  
Yu Yong Chen ◽  
Yong Jun Su ◽  
Fan Tao Kong ◽  
De Liang Zhang
Keyword(s):  
Intermetallic Compounds ◽  
Lamellar Structure ◽  
Tial Alloy ◽  
Lower Cost ◽  
Hot Forging ◽  
Processing Route ◽  
Blended Elemental ◽  
Powder Blending ◽  
Process Route ◽  
Fully Lamellar

Ti-43Al-5V-4Nb (at.%) intermetallic compounds with fully lamellar structure were fabricated by forging method without canning using the blended elemental powders. The process route consisted of powder blending, compacting, sintering and final fabrication by hot forging. During sintering, there existed expansion, which is detrimental to forging process. In order to overcome the difficulty, two-step forging was introduced. The total reduction of two-step forging was up to 65%. Nearly fully lamellar structure of TiAl alloy was obtained. Overall, an optimized and potentially lower cost processing route could be identified.

Ductile TiAl alloy with a Widmanstätten lamellar structure formed by rapid heating

2008 ◽  
Vol 23 (4) ◽  
pp. 949-953 ◽  
Author(s):  
J.P. Cui ◽  
M.L. Sui ◽  
Y.Y. Cui ◽  
D.X. Li
Keyword(s):  
Electric Current ◽  
Lamellar Structure ◽  
Tial Alloy ◽  
Rapid Heating ◽  
Pulse Treatment ◽  
Electric Current Pulse ◽  
Microstructural Refinement ◽  
Tial Alloys ◽  
Refinement Mechanism ◽  
Fully Lamellar

Instead of conventional grain-refinement treatments for improving the ductility of fully lamellar TiAl alloys, multiorientational, lamellar, subcolony refinement with good ductility has been achieved simply by using an electric-current pulse treatment. The microstructural refinement mechanism is attributed to the transformation on heating of γ laths in the prior large-grain lamellar structure to Widmanstätten α in several orientations, which on subsequent cooling forms lamellar structure colonies in multiple orientations. This kind of refined multiple-colony lamellar structure was found to enhance the ductility of the TiAl alloy.

Beneficial Effects of Boron Addition into γ-TiAl Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1451-1456 ◽  
Author(s):  
Z.X. Li ◽  
Xia Huang ◽  
L.C. Qi ◽  
Chun Xiao Cao
Keyword(s):  
Lamellar Structure ◽  
Tial Alloy ◽  
Eutectic Reaction ◽  
Rupture Life ◽  
Boron Addition ◽  
Tial Alloys ◽  
Beneficial Effects ◽  
Rich Alloy ◽  
Fully Lamellar ◽  
Thermal Stability Of

The beneficial effects of boron addition on microstructure transformations and mechanical properties of γ-TiAl alloys were investigated. Two growth mechanisms of boride (TiB2) in γ-TiAl alloy were confirmed, the curved flaky borides are products of irregular eutectic reaction growing coupled with matrix, while some faceted blocky borides in boron-rich alloy are primary TiB2 phase growing directly in melt. The core of flaky TiB2 is ultra-fine B2 phase and there has an orientation relationship [1210] TiB2//[001]B2, (1010) //(010)B2. In addition to the well-known grain refinement effect, boron addition can suppress the formation of metastable feathery and Widmastätten structure and broadens cooling-rate-range for the formation of fully lamellar structure, consequently, it improves thermal stability of the lamellar structure and accordingly prolongs the creep rupture life significantly. Another beneficial effect of boron addition is that boride can restrain discontinuous coarsening on lamellar grain boundary by pinning action and accelerates recrystallization of γ grain by introducing TiB2/matrix interfaces as nuclear sites during homogeneous treatment at 1150°C. Therefore, compared with boron-free alloy more homogeneous and refined near γ microstructure can be obtained in boron modified alloy.

Role of lamellar plates in creep of TiAl alloy with fully lamellar structure

2002 ◽  
Vol 329-331 ◽  
pp. 774-779 ◽  
Author(s):  
T Matsuo ◽  
T Nozaki ◽  
T Asai ◽  
M Takeyama
Keyword(s):  
Lamellar Structure ◽  
Tial Alloy ◽  
Fully Lamellar

Interfacial strengthening of β phase in a fully lamellar structure of TiAl alloy containing W

2005 ◽  
Vol 85 (7) ◽  
pp. 377-385 ◽  
Author(s):  
H. Zhu * ◽  
D. Y. Seo ◽  
K. Maruyama ◽  
P. Au
Keyword(s):  
Lamellar Structure ◽  
Tial Alloy ◽  
Β Phase ◽  
Fully Lamellar

Influence of the Grain Size of Fully Lamellar Structure on the Mechanical Properties of a TiAl Based Alloy

1994 ◽  
Vol 364 ◽  
Author(s):  
Z. J. Pu ◽  
J. L. Ma ◽  
K. H. Wu
Keyword(s):  
Mechanical Properties ◽  
Yield Stress ◽  
Colony Size ◽  
Lamellar Structure ◽  
Tial Alloy ◽  
Preliminary Investigation ◽  
Petch Relation ◽  
Large Colony ◽  
Small Colony ◽  
Fully Lamellar

AbstractA preliminary investigation was conducted for developing a thermomechanical procedure to refine the lamellar colony size of a fully lamellar structure and improve the balance of the mechanical properties of TiAl based alloys. The main experimental results are as follows: 1) The lamellar colony size in a fully lamellar structure can be reduced to 50 μm using a proper thermomechanical procedure. 2) The influence of colony size on the compressive yield stress of the fully lamellar structure is complex. In the large colony size region, the yield stress can be described by the Hall-Petch relation. In the small colony size region, the yield stress decreases as the colony size decreases. 3) The TiAl alloy, with a fine fully lamellar structure, has the best balance of tensile properties and fracture toughness.

scholarly journals Effect of Microstructure Control on the Mechanical Properties of Hot Worked TiAl Alloy

2020 ◽  
Vol 58 (7) ◽  
pp. 459-465
Author(s):  
Jong-hun Kim ◽  
Jae-Kwon Kim ◽  
Seong-Woong Kim ◽  
Yong-Ho Park ◽  
Seung Eon Kim
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Lamellar Structure ◽  
Room Temperature ◽  
Tial Alloy ◽  
Post Heat Treatment ◽  
Β Phase ◽  
Fully Lamellar ◽  
Strength And Ductility

The microstructure and mechanical properties of a newly developed, β-phase containing TiAl alloy have been studied through hot working and post heat treatment to enhance room temperature ductility and strength. The controlled microstructures hadthree types of structure, fully lamellar, nearly lamellar and duplex, and were produced by cyclic heat-treatment in a single α region and (α+γ) region after a hot-forging process in high temperature (α+β) region. As a result of the room temperature tensile test, the fully lamellar structure exhibited a tensile strength of 622 MPa and ductility of 0.62%. The duplex structure had a tensile strength of 787 MPa and ductility of 1.22%, while the nearly lamellar structure showed a tensile strength of 880 MPa and ductility of 1.76%. In the room temperature tensile test, the nearly lamellar structure exhibited excellent tensile strength and ductility. The strength and ductility were increased by decreasing grain size and β / B2 phase fraction. The newly developed TiAl alloy showed higher tensile values compared with the previous TiAl alloys. The relationship between microstructure and room temperature tensile properties of the newly developed β-phase containing TiAl alloy was examined, and the best approach for hot working and post heat-treatment to obtain the most balanced mechanical properties was proposed.

scholarly journals Creep of a fine-grained, fully-lamellar, two-phase TiAl alloy at 760{degree}C

10.2172/46701 ◽  
1995 ◽  
Author(s):  
J.N. Wang ◽  
A.J. Schwartz ◽  
T.G. Nieh ◽  
C.T. Liu ◽  
V.K. Sikka ◽  
...  
Keyword(s):  
Tial Alloy ◽  
Two Phase ◽  
Fine Grained ◽  
Fully Lamellar

Effects of Ca and RE Additions on the Precipitation and Microstructure of As-Cast AZ91 Alloy

2017 ◽  
Vol 865 ◽  
pp. 30-35 ◽  
Author(s):  
Li Fu ◽  
Qi Chi Le ◽  
Pei Li Gou ◽  
Xi Bo Wang ◽  
Xuan Liu
Keyword(s):  
Intermetallic Compound ◽  
Grain Boundaries ◽  
Intermetallic Compounds ◽  
Lamellar Structure ◽  
Az91 Alloy ◽  
Sem Images ◽  
Xrd Pattern ◽  
Microstructure Changes ◽  
Polygonal Structure ◽  
Cast Alloys

The effect of Ca and RE metal additions on the precipitation and microstructure of as-cast AZ91 alloy was systematically investigated. It was found that Ca and RE additions could result in phase and microstructure changes. The XRD pattern showed the crystallite phase of as-cast AZ91 alloys consists of α-Mg matrix and β-Mg17Al12, however, after adding 1.5wt. % Ca and 0.8wt. % RE (0.5wt. % Sm and 0.3wt. % La), peaks coincident with Al2Ca, Al2Sm and Al11La3 intermetallic compounds were found, suggesting the generation of relative precipitates. The SEM images indicated that in as-cast alloys, the Al2Ca intermetallic compound was located at grain boundaries with a lamellar structure, and the Al2Sm intermetallic compound was homogeneously distributed in the α-Mg matrix or near the grain boundaries with a polygonal structure, and the Al11La3 intermetallic compound was located at grain boundaries with a needlelike structure. These intermetallic compounds could reduce the amount of β-Mg17Al12 and refine the microstructure of as-cast AZ91 alloy.

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