Fine grained fully lamellar structure acquisition and microstructure characteristics of Ti-44Al-4Nb-4V-0.3Mo-Y alloy

2018 ◽  
Vol 144 ◽  
pp. 141-147 ◽  
Author(s):  
S.Z. Zhang ◽  
Z.W. Song ◽  
C.J. Zhang ◽  
J.C. Han ◽  
Y.B. Zhao ◽  
...  
Keyword(s):  
Lamellar Structure ◽  
Microstructure Characteristics ◽  
Fine Grained ◽  
Fully Lamellar

Influence of Step Aging on Creep Behavior and Microstructural Evolution of Fine-Grained Fully Lamellar XD TiAl Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1525-1530
Author(s):  
Han Liang Zhu ◽  
Dong Yi Seo ◽  
Kouichi Maruyama ◽  
Peter Au
Keyword(s):  
Creep Rate ◽  
Microstructural Evolution ◽  
Creep Behavior ◽  
Creep Deformation ◽  
Lamellar Structure ◽  
Aging Condition ◽  
Tial Alloys ◽  
Fine Grained ◽  
Fully Lamellar ◽  
Multiple Step

Fine-grained fully lamellar (FGFL) structures of XD TiAl alloys (Ti-45 and 47Al-2Nb-2Mn+0.8vol.%TiB2) (at.%) were stabilized to varying degrees by different aging treatments. Specimens with and without aging were creep tested at 760°C and 207 MPa. It was found that during creep deformation, degradation of the lamellar structure involving coarsening within the colonies and spheroidization at colony boundaries occurred, forming fine globular structures at the colony boundaries and increasing the creep rate. Aging treatments stabilized the lamellar structure and retarded the coarsening and spheroidization processes during creep deformation. As a result, the aged specimens exhibited lower minimum creep rates and longer creep lives than the unaged specimens. A multiple step aging stabilized the lamellar structure to the greatest extent and suppressed other degradation processes during aging, resulting in the best creep resistance. These results demonstrate that the multiple step aging is the optimal aging condition for stabilizing FGFL XD TiAl alloys.

Effect of Heat Treatment on Microstructure and Mechanical Property of 45XD and 47XD TiAl Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 581-584 ◽  
Author(s):  
H. Zhu ◽  
Dong Yi Seo ◽  
Kouichi Maruyama
Keyword(s):  
Heat Treatment ◽  
Mechanical Property ◽  
Lamellar Structure ◽  
Tial Alloys ◽  
Fine Grained ◽  
Break Up ◽  
Fully Lamellar ◽  
Hardness Values ◽  
Microstructure And Mechanical Property ◽  
Microstructural Examination

The effect of heat treatment on microstructure and property of Ti-45 and 47Al-2Nb-2Mn+0.8%vol.%TiB2 alloys (45XD and 47XD) has been studied. Annealing and subsequent oil quench produced fine-grained fully lamellar structure (FGFL) in both alloys. For microstructural stabilization, the FGFL structures were subjected to different aging treatments. Microstructural examination showed that degradation of the FGFL structure, such as coarsening of γ lamellae, recrystallization of γ grains and break-up of a2 lamellae, presented to varying degrees after different aging treatments. Hardness values in the aged alloys decreased due to the degradation. The creep resistances were improved in the aged alloys though the degradation occurred, indicating that the aging treatments stabilized the FGFL structures effectively. The differences in the changes of properties caused by different aging treatments and compositions were compared in combination with the microstructural variants.

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

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.

Hot deformation behavior and processing maps of Ti–6Al–4V alloy with starting fully lamellar structure

2018 ◽  
Vol 33 (22) ◽  
pp. 3677-3688 ◽  
Author(s):  
Wenjing Zhang ◽  
Hua Ding ◽  
Jingwei Zhao ◽  
Bo Yang ◽  
Wenjing Yang
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Lamellar Structure ◽  
Processing Maps ◽  
Hot Deformation Behavior ◽  
Image Position ◽  
Fully Lamellar

Abstract

C11b/C40 Lamellar Structure in a Ta-added Molybdenum Disilicide

2000 ◽  
Vol 646 ◽  
Author(s):  
Fu-Gao Wei ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Mechanical Properties ◽  
Orientation Relationship ◽  
Binary Alloy ◽  
Lamellar Structure ◽  
Molybdenum Disilicide ◽  
Lamellar Microstructure ◽  
Polycrystalline Alloys ◽  
Lamellar Interface ◽  
Fully Lamellar ◽  
Microstructural Control

ABSTRACTC11b/C40 fully lamellar microstructures, similar to the well-known TiAl/Ti3Al lamellae, were obtained in Ta- and Nb-added MoSi2 polycrystalline alloys in a previous work. In the present study, the crystallography of the lamellar structure is investigated in a MoSi2-15mol%TaSi2 pseudo-binary alloy after homogenized at 1400°C for 168h, in order to provide some useful parameters for microstructural control to improve mechanical properties. The orientation relationship between C11b and C40 phases and its three distinct variants were identified. Coherency of the lamellar interface is analyzed in comparison with the TiAl/Ti3Al lamellae. Approach to modify the C11b/C40 lamellar microstructure to increase its coherency is discussed based on the results obtained.

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.

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