Lamellar orientation and growth direction of α phase in directionally solidified Ti-46Al-0.5W-0.5Si alloy

2012 ◽  
Vol 27 ◽  
pp. 38-45 ◽  
Author(s):  
Xinzhong Li ◽  
Jianglei Fan ◽  
Yanqing Su ◽  
Dongmei Liu ◽  
Jingjie Guo ◽  
...  
Keyword(s):  
Growth Direction ◽  
Directionally Solidified ◽  
Α Phase ◽  
Lamellar Orientation

Growth Directions of Primary Phases in Directionally Solidified Ti-45Al-7Nb Alloys

2013 ◽  
Vol 32 (1) ◽  
pp. 69-75
Author(s):  
Jie Yan ◽  
Lijing Zheng ◽  
HuaRui Zhang ◽  
Zhixia Xiao ◽  
Hu Zhang
Keyword(s):  
Deflection Angle ◽  
Primary Dendrite ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Electron Backscattered Diffraction ◽  
Lamellar Orientation ◽  
Primary Dendrite Arm Spacing ◽  
The Deflection Angle ◽  
Solidification Pathway ◽  
Liquid Metal Cooling

AbstractTi-45Al-7Nb alloys are produced by liquid-metal-cooling (LMC) directional solidification (DS) furnace with different temperature gradients (G) at a range of 40–80 K/cm. The growth directions of primary β phases and the deflection angles relative to the 〈100〉β direction were investigated. The solidification pathway of alloy is: Liq. → Liq. + β → β → β + α → α + γ → lamella (α2 + γ) + B2. Primary dendrite arm spacing λ reduced from 611.4 µm to 508.7 µm when G increased from 40 K cm−1 to 80 K cm−1. Grains with lamellar orientation aligned at the angles of 12–15° and 55° to growth direction were favored for various G. The orientations of the γ lamellas in steady-state regions were identified by the electron backscattered diffraction analysis (EBSD). The results indicated that the growth directions of primary bcc-β dendrites were 〈211〉β and 〈110〉β at 40 K/cm, 〈210〉β and 〈211〉β at 50 K/cm and 〈211〉β at 80 K/cm, the deflection angle of 〈211〉β relative to 〈100〉β direction is 35.3°.

Deformation of Diffusion-Bonded Bi-Pst and Directionally Solidified Crystals of TiAl

1996 ◽  
Vol 460 ◽  
Author(s):  
K. Kishida ◽  
D. R. Johnson ◽  
Y. Shimada ◽  
Y. Masuda ◽  
H. Inui ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Diffusion Bonding ◽  
Flow Behavior ◽  
Lamellar Microstructure ◽  
Growth Direction ◽  
Current Status ◽  
Directionally Solidified ◽  
Lamellar Orientation ◽  
Columnar Grain ◽  
And Diffusion

ABSTRACTWith a data base now available on the microstructural characteristics and the deformation, fracture and macroscopic flow behavior of polysynthetically twinned (PST) crystals of γ/α2 TiAl-base alloys, an approach to achieve a good combination of strength, ductility and toughness in γ/α2 TiAl-base alloys was proposed using directional solidification (DS) techniques to produce a columnar grain material with the lamellar orientation aligned parallel to the growth direction. Such alignment of the lamellar microstructure was recently accomplished in γ/α2 TiAl-base alloys of near equiatomic compositions using an appropriately oriented seed crystal from the Ti-Al-Si system.At the same time, bi-PST crystals, each containing a planar boundary parallel to the loading axis were prepared by directional solidification and diffusion bonding of two PST crystals. Such bi-PST crystals were deformed in tension at room temperature and their deformation behavior was examined in terms of the compatibility requirements imposed at the grain boundary and the interaction of the two component PST crystals.In this paper, (i) the current status of our DS processing efforts, (ii) some results of microscopic characterization of grain boundaries in diffusion bonded bi-PST crystals and (iii) results of deformation experiments of bi-PST crystals prepared by DS processing and diffusion bonding, will be reported.

Effects of solidification parameters on the growth direction of α phase in directionally solidified Ti-49Al alloy

2017 ◽  
Vol 90 ◽  
pp. 113-118 ◽  
Author(s):  
Jianglei Fan ◽  
Chi Zhang ◽  
Shen Wu ◽  
Hongxia Gao ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Growth Direction ◽  
Directionally Solidified ◽  
Α Phase ◽  
Solidification Parameters

Effects of Initial Nucleation Condition at the Start Block on the Grain Size and Growth Direction in Directionally Solidified CM247LC Superalloy

2011 ◽  
Vol 49 (01) ◽  
pp. 58-63
Author(s):  
Hye-Young Yoon ◽  
Je-Hyun Lee ◽  
Hyeong-Min Jung ◽  
Seong-Moon Seo ◽  
Chang-Young Jo ◽  
...  
Keyword(s):  
Grain Size ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Initial Nucleation

Hydrogen Permeation Properties of Nb-Based Two-Phase Compounds

2007 ◽  
Vol 561-565 ◽  
pp. 467-470
Author(s):  
Yuji Yamaguchi ◽  
Kyosuke Kishida ◽  
Katsushi Tanaka ◽  
Haruyuki Inui ◽  
Sho Tokui ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Permeation ◽  
Membrane Surface ◽  
Hydrogen Permeability ◽  
Eutectic Structure ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Two Phase ◽  
Cast Sample ◽  
Lamellar Type

Nb-NiTi and Nb-CoTi eutectic alloys were directionally solidified in an optical floating zone furnace. Rod-type eutectic structures with Nb rods aligned parallel to the growth direction are obtained for Nb-41Ni-40Ti grown at relatively slow growth rates below 1.0mm/h, while lamellar-type eutectic structures are obtained for Nb-35Co-34Ti grown at the same condition. The hydrogen permeability for the Nb-41Ni-40Ti DS alloy with Nb rods perpendicular to the membrane surface is 2.60×10-8mol H2 m-1 Pa-1/2 at 673K, which is about 2.5 times higher than that of as-cast sample. No hydrogen embrittlement is observed between 573 and 673K, indicating that the Nb-NiTi rod-type eutectic structure effectively suppresses the hydrogen embrittlement of Nb during hydrogen permeation.

Microstructure and Mechanical Properties of Ti-6Al-4V Alloy Samples Fabricated by Selective Laser Melting

2018 ◽  
Vol 770 ◽  
pp. 179-186 ◽  
Author(s):  
Jing Bo Gao ◽  
Xiao Li Zhao ◽  
Ju Kun Yue ◽  
Meng Chao Qi ◽  
De Liang Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Crystal Growth ◽  
Yield Strength ◽  
Selective Laser Melting ◽  
Lamellar Structure ◽  
Growth Direction ◽  
Laser Melting ◽  
Α Phase ◽  
Dog Bone

Ti-6Al-4V (wt%) alloy samples with dog-bone and box shapes respectively were fabricated by selective laser melting (SLM). The microstructures and mechanical properties of the 3D printed Ti-6Al-4V samples with and without heat treatment were characterized and tested. The microstructures of the as-fabricated dog-bone shaped samples were mainly composed of acicular α’ phase. After annealing at 700°C, the acicular α’ phase changed into an α/β lamellar structure. After solution treatment at 955°C, water quenching and aging at 550°C, the microstructure was mainly composed of primary α phase and α/β lamellar structure. The optimum heat treatment is annealing, and the mechanical properties of the annealed sample are as follows: yield strength: 1015 MPa, ultimate tensile strength (UTS): 1083 MPa and elongation to fracture: 7.9%. The microstructures of the box-shaped samples after annealing mainly consist of α phase and α/β lamellar structure. When stretched along the direction parallel to the crystal growth direction, the yield strength and UTS of the sample are 1054 and 1090 MPa，and its elongation to fracture is 6.3%. When stretched along the direction perpendicular to the crystal growth direction, the yield strength and UTS of the sample are 1019 and 1068 MPa respectively, and its elongation to fracture is 8.7%.

Microstructure and Mechanical Properties of a Rapid Directionally Solidified Ti47Al Alloy

2011 ◽  
Vol 117-119 ◽  
pp. 217-221
Author(s):  
Rui Run Chen ◽  
Hong Sheng Ding ◽  
Jing Jie Guo ◽  
Yan Qing Su ◽  
Heng Zhi Fu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Grain Growth ◽  
Axial Direction ◽  
Longitudinal Section ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Compressive Properties ◽  
Dendritic Core ◽  
Columnar Grains

The ingot of Ti47Al alloy was prepared by a newly developed rapid directional solidification, the microstructure and compressive properties of the ingot was observed and tested. The results show that the macrostructure consisted mainly of coarse columnar grains parallel to the axial direction, with the size of 0.5mm wide and 10mm in length. The direction of lamellar is almost perpendicular to the growth direction in the longitudinal section and no dendritic core is found. The average ultimate compressive strength of the specimens with grain growth parallel/perpendicular to the compressive direction is 1233.3 and 861.7 MPa respectively. The fracture mode for specimens with grain growth parallel to the compressive direction exhibits predominantly translamellar fracture, however, that for specimens with grain growth perpendicular to the compressive direction exhibits predominantly delamenation or interlamellar fracture.

Microstructures and Mechanical Properties of MoSi2 / Mo5Si3 / Mo5Si3C Ternary Eutectic Composite

2015 ◽  
Vol 1760 ◽  
Author(s):  
Hirotaka Matsunoshita ◽  
Kosuke Fujiwara ◽  
Yuta Sasai ◽  
Yuichiro Kondo ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ternary Eutectic ◽  
Growth Direction ◽  
Compression Tests ◽  
Eutectic Composite ◽  
Directionally Solidified ◽  
Microstructures And Mechanical Properties ◽  
Image Position ◽  
Lamellar Type ◽  
Crystalline Matrix

ABSTRACTMicrostructures and mechanical properties of directionally solidified (DS) MoSi2 / Mo5Si3 / Mo5Si3C ternary eutectic composites were investigated. Ternary eutectic microstructure of a script-lamellar type that is characterized by rod-shaped Mo5Si3 and Mo5Si3C phases extending along the growth direction in the MoSi2 single crystalline matrix was developed simply by directional solidification at a growth rate of 10 mm/h. Compression tests along $[{\rm{1}}\mathop 1\limits^- 0]_{MoSi_2 }$ nearly parallel to the growth direction revealed that the DS ternary eutectic composites were plastically deformed above 1000 °C. Yield stresses of the DS ternary eutectic composites were much higher than those of binary composites mainly because of a smaller average thickness of MoSi2 matrix.

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