Effects of Ternary Additions on the Microstructure of Directionally-Solidified MoSi2/Mo5Si3 Eutectic Composites

2013 ◽  
Vol 1516 ◽  
pp. 189-194 ◽  
Author(s):  
Kosuke Fujiwara ◽  
Yuta Sasai ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Inclination Angle ◽  
Growth Direction ◽  
Ternary Addition ◽  
Directionally Solidified ◽  
Ternary Additions ◽  
Significant Change

ABSTRACTMicrostructural variations of directionally-solidified (DS) MoSi2/Mo5Si3 eutectic composites caused by ternary additions of V, Cr, Nb, Ta and W were investigated. Ternary addition of relatively large amount of V resulted in the apparent modification of the morphology as well as the macroscopic inclination angle of one type of the interfaces extending nearly along the growth direction in the DS ingots. Ternary addition of Cr was found to change the microstructures of the DS ingots from a cellular-type with coarse boundary regions to a plate-like cellular-type with increasing the amount of the ternary addition. No significant change of scriptlamellar morphology was observed for the DS ingots containing Nb, Ta and W irrespective of the amount of the ternary addition.

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.

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.

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.

INTEGRALLY DIRECTIONALLY SOLIDIFIED MICROSTRUCTURE OF AN NIOBIUM SILICIDE BASED ULTRAHIGH TEMPERATURE ALLOY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1093-1098 ◽  
Author(s):  
XIPING GUO ◽  
HAISHENG GUO ◽  
CHENGFANG YAO ◽  
PING GUAN
Keyword(s):  
Average Diameter ◽  
Lamellar Spacing ◽  
Growth Direction ◽  
Solidification Path ◽  
Eutectic Cell ◽  
Directionally Solidified ◽  
Melt Temperature ◽  
Eutectic Morphology ◽  
Ultrahigh Temperature ◽  
Solid Liquid

Integrally directional solidification of an advanced Nb silicide based ultrahigh temperature alloy was conducted with the use of special ceramic crucibles. The melt temperature was 2000°C and the withdrawing rate was respectively 5, 10, 15, 30, 50, 80 and 100 µm/s. The directionally solidified microstructure was composed of primary ( Nb ,X)5 Si 3 rods and ( Nb , Ti ) ss + ( Nb ,X)5 Si 3 eutectic colonies (here X represents Ti and Hf elements) that distributed evenly and aligned erectly along the growth direction. The quenched solid/liquid (S/L) interfaces had the morphology of a series of protruded parallel eutectic cells along the growth direction. ( Nb , Ti ) ss and ( Nb ,X)5 Si 3 slices grew in a coupled manner in each eutectic cell, forming a typical lamellar eutectic morphology. Both the average diameter of eutectic cells and lamellar spacing in them decreased with the increase of withdrawing rates. The solidification path was that primary ( Nb ,X)5 Si 3 rods formed firstly and then the retained liquid around solidified into ( Nb , Ti ) ss + ( Nb ,X)5 Si 3 eutectic cells.

scholarly journals Effects of ternary additions on the microstructure and thermal stability of directionally-solidified MoSi2/Mo5Si3 eutectic composites

2014 ◽  
Vol 52 ◽  
pp. 72-85 ◽  
Author(s):  
Kosuke Fujiwara ◽  
Hirotaka Matsunoshita ◽  
Yuta Sasai ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Thermal Stability ◽  
Directionally Solidified ◽  
Ternary Additions ◽  
Thermal Stability Of

Plastic Deformation of Directionally-Solidified MoSi2/Mo5Si3 Eutectic Composites

2013 ◽  
Vol 1516 ◽  
pp. 195-200 ◽  
Author(s):  
Yuta Sasai ◽  
Atsushi Inoue ◽  
Kosuke Fujiwara ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Growth Direction ◽  
Average Thickness ◽  
Floating Zone ◽  
Directionally Solidified ◽  
Zone Method ◽  
Increasing Temperature ◽  
Loading Axis

ABSTRACTDeformation behavior of the directionally-solidified MoSi2/Mo5Si3 eutectic composites has been investigated as a function of the average thickness of MoSi2 phase over a temperature range from 900 to 1500°C. The average thickness of both MoSi2 and Mo5Si3 phases in the directionally-solidified ingots with script-lamellar morphologies grown by optical floating zone method decreases with increasing the growth rate. Plastic deformation was observed above 1000°C for all the DS ingots grown at different growth rates when the loading axis is parallel to [1¯10]MoSi2 close to the growth direction. Yield stress decreases monotonically with increasing temperature. Yield stress at 1400°C increases drastically with decreasing the average thickness of MoSi2 phase.

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