Axial Alignment of Short-Fiber Titanium Aluminide Composites by Directional Solidification

1990 ◽  
Vol 194 ◽  
Author(s):  
S. L. Kampe ◽  
G. H. Swope ◽  
L. Christodoulou
Keyword(s):  
Aspect Ratio ◽  
Plastic Strain ◽  
Directional Solidification ◽  
Titanium Aluminide ◽  
Base Material ◽  
Short Fiber ◽  
Floating Zone ◽  
Microstructural Evaluation ◽  
The Matrix

AbstractThe floating zone directional solidification technique has been applied to an XDTM short-fiber-reinforced titanium aluminide ingot in an effort to produce in situ alignment of the reinforcement. Microstructural evaluation reveals that a general alignment of the high aspect ratio (>100:1) fibers occurs under specific imposed solidification conditions. These metallographic observations are supported by 800 ° C mechanical data, which indicate higher axial and reduced transverse strengths relative to the unprocessed base material which contains a dispersion of randomly oriented fibers. The increased strengths are observed to be a consequence of an increase in the matrix hardening due to accommodation of plastic strain around the fiber reinforcement.

Directional Solidification of Refractory Intermetallics: Single Crystals and Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
David P. Pope ◽  
Dilip M. Shah ◽  
William Romanow ◽  
Mark Huntley
Keyword(s):  
Aspect Ratio ◽  
Optical Imaging ◽  
Directional Solidification ◽  
Single Crystals ◽  
Intermetallic Compounds ◽  
Floating Zone ◽  
Growth Axis ◽  
Advantages And Disadvantages

AbstractDirectional solidification of intermetallic compounds using the optical imaging floating zone technique is discussed. The advantages and disadvantages of the technique are described, and the systems to which this technique has been applied are listed. Finally, application of the technique to growing in situ Cr2Nb/Nb composites is described. It is shown that well aligned, fine microstructures can be obtained using the technique. The aspect ratio of the Cr2Nb platelets is 200:1, or better, and are a few microns thick. The Cr2Nb has a strong <220> texture along the growth axis but the Nb is nearly random.

In Situ Produced MMC Layer by Laser Melt Injection

2010 ◽  
Vol 649 ◽  
pp. 61-66
Author(s):  
Zoltán Kálazi ◽  
Viktória Janó ◽  
Gábor Buza
Keyword(s):  
Carbon Content ◽  
Composite Layer ◽  
Pure Titanium ◽  
Base Material ◽  
Titanium Content ◽  
Steel Sample ◽  
Low Carbon ◽  
The Matrix ◽  
Ti Powder

Tungsten (W) based alloy composite layer reinforced with TiC particles has been successfully prepared on unalloyed steel sample by LMI technology. In order to obtain in situ produced TiC reinforcement, pure titanium has been introduced to the melt pool. WC powder was added for increasing the carbon content of the layer in order to avoid the softening of the matrix (with low carbon content) during TiC formation. The present study aims to investigate the optimum amount of injected WC and Ti powder to improve wear resistance and hardness of the layer. Samples were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum hardness of the layer has been reached ~900HV in case of 2-4wt% of titanium content. Ti has been collected all of the carbon from the matrix when titanium content was 9,6wt%, which resulted that the austenite and (Fe,W)6C phases have been disappeared. Only α-Fe and TiC phases were presented in the layer. The hardness of the layer reduced to the hardness of the base material.

Micromechanics-based analyses of short fiber-reinforced composites with functionally graded interphases

2019 ◽  
Vol 54 (8) ◽  
pp. 1031-1048 ◽  
Author(s):  
Yang Yang ◽  
Qi He ◽  
Hong-Liang Dai ◽  
Jian Pang ◽  
Liang Yang ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Elastic Properties ◽  
Effective Properties ◽  
Micromechanical Model ◽  
Short Fiber ◽  
Functionally Graded ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
The Matrix

A micromechanical model for short fiber-reinforced composites (SFRCs) with functionally graded interphases and a systematic prediction scheme to determine the effective properties are presented. The matrix and the fibers are regarded to be linear elastic, isotropic, and homogeneous. Fibers are assumed to be ellipsoids coated perfectly by functionally graded interphases, which is supposed to be formed chemically or physically by the constituents near the interface. First, to analyze the grading interphase effect, layer-wise concept is followed to divide the functionally graded interphases into multi-homogeneous sub-layers. Next, to take the effect of functionally graded interphases into account, a combination of multi-inclusion method and Mori–Tanaka method is applied to predict effective elastic properties of this unidirectional SFRCs with respect to the content and aspect ratio of the inclusions. By employing coordinate transformation, spatially elastic moduli are obtained. Finally, Voigt homogenization scheme is used to obtain the overall, averaged, symmetrical elastic properties of the SFRCs. Numerical examples and analyses demonstrate the applicability of the proposed method and indicate the influences of graded interphase, orientation, and aspect ratio of inclusions as well as properties and contents of the constituents on the overall properties of SFRCs.

Solidification Processing Routes to High Aspect Ratio Reinforcements in γ-TiAl

1990 ◽  
Vol 194 ◽  
Author(s):  
J. J. Valencia ◽  
J. P. A. Löfvander ◽  
J. Rösler ◽  
C. G. Levi ◽  
R. Mehrabian
Keyword(s):  
Solid Solution ◽  
Aspect Ratio ◽  
Creep Strength ◽  
High Aspect Ratio ◽  
Anisotropic Growth ◽  
Solidification Processing ◽  
Aspect Ratios ◽  
The Matrix ◽  
Solute Strengthening

AbstractAdditions of ∼5%B1 and ∼9%Ta to binary γ-TiAl result in the formation of a monoboride isomorphous with TiB but containing Ta in solid solution. This boride exhibits strongly anisotropic growth from the melt, producing rod-like primary phases which are of potential interest for creep strengthening of the γ matrix. Fibrous borides with aspect ratios larger than ∼20 and volume fractions of ∼0.12 have been produced in arc-melted Ti-48AI-9Ta-4.3B alloys. Creep testing at 1255 K indicates that these “in-situ” composites have much higher creep strength than γ-TiAl, but the contribution of the reinforcements is relatively small compared with the solute-strengthening of the matrix.

Reaction Synthesis of TiAl-Al2O3 Composites from Ti-Al-Cr2O3

2011 ◽  
Vol 211-212 ◽  
pp. 209-212
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Fang Ni Du
Keyword(s):  
Solid State ◽  
Titanium Aluminide ◽  
Reaction Synthesis ◽  
Hot Press ◽  
Prepared Material ◽  
The Matrix ◽  
Press Method ◽  
Ti Powder

Titanium aluminide composite reinforced with in situ formed submicron Al2O3 has been prepared by a reactive hot press method using Cr2O3, Al and Ti powder as starting materials. The reaction synthesis processing is particularly investigated. Results show that the matrix of the as-prepared material is a mixture of TiAl and a small amount of Ti3Al and Cr containing phase. Fine Al2O3 particles that act as reinforcing phase are dispersed along the interface of the matrix. The formation of TiAl/Al2O3 composite involves many transitional stages. Firstly, TiAl3 and Ti3Al intermediates were produced, then reducing reaction of Cr2O3 by Al formed Al2O3, and finally, the competitive solid-state diffusing reactions among Ti3Al, TiAl and TiAl3 produced the matrix phases of the TiAl/Al2O3 composite.

Effect of HfC Addition on Mechanical Properties of Nb-5Mo-2W-18Si In-Situ Composites

2004 ◽  
Vol 261-263 ◽  
pp. 1439-1444 ◽  
Author(s):  
Sheng Wu Wang ◽  
Hisatoshi Hirai ◽  
Tatsuo Tabaru ◽  
A. Kitahara ◽  
Hideto Ueno
Keyword(s):  
Mechanical Properties ◽  
Directional Solidification ◽  
Base Composition ◽  
Zone Melting ◽  
Shearing Stress ◽  
Floating Zone ◽  
In Situ Composites ◽  
Arc Melting ◽  
Microcrack Propagation

Nb base in-situ composites with the base composition of Nb-5Mo-2W-18Si were prepared by conventional arc-melting and induction heating floating zone melting followed by directional solidification. To investigate the effect of HfC addition, Nb was replaced with 0, 1 and 2 mol% HfC. The in-situ composites predominantly have an eutectic microstructure consisting of Nb solid solution (NbSS) and (Nb,Mo,W))5Si3 (5-3 silicide). The strength at 1470 K and 1670 K increases without fracture toughness decreasing, with increasing the HfC content. Directional solidification also improves the strength at the high temperature. The slip band under the shearing stress occurs in the NbSS during plastic deformation, which contributes to suppress microcrack propagation. It seems that HfC addition reinforces the bonding strength at grain boundary or NbSS/5-3 silicide interface.

Structure/Property Comparisons in Particulate and Short Fiber γ-Based Titanium Aluminide Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
S. L. Kampe ◽  
J. A. Clarke ◽  
L. Christodoulou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Titanium Aluminide ◽  
Tensile Ductility ◽  
Short Fiber ◽  
Structure Property ◽  
Volume Percent ◽  
Matrix Microstructure ◽  
The Matrix ◽  
Fully Lamellar

AbstractThe effect of matrix microstructure on the mechanical properties of two model XD™ titanium aluminide composites containing 7 volume percent of either particulate (TiB2) or short-fiber ((Ti,Nb)By) reinforcement has been evaluated. Subsequent to wrought-processing via isothermal forging, heat treatments were performed to produce either a fully equiaxed or fully lamellar matrix microstructure. The synergism between matrix microstructure and reinforcement type has been evaluated for ambient-temperature tensile ductility and fracture toughness, and 800°C tensile strength and creep rate. Results indicate that overall composite performance is strongly dependent on reinforcement shape, the extent of which depends on the morphology of the matrix microstructure.

Directional solidification of Ni–Ni3Si eutectic in situ composites by electron beam floating zone melting

2013 ◽  
Vol 412 ◽  
pp. 70-73 ◽  
Author(s):  
Chunjuan Cui ◽  
Jun Zhang ◽  
Kun Wu ◽  
Dening Zou ◽  
Youping Ma ◽  
...  
Keyword(s):  
Electron Beam ◽  
Directional Solidification ◽  
Zone Melting ◽  
Floating Zone ◽  
In Situ Composites
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