The Effects of in-Situ Processing Methods on the Microstructure and Fracture Toughness of V-V3Si Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
M. J. Strum ◽  
G. A. Henshall ◽  
B. P. Bewlay ◽  
J. A. Sutliff ◽  
M. R. Jackson
Keyword(s):  
Fracture Toughness ◽  
Synthesis Method ◽  
Solid Solution Phase ◽  
Synthesis Methods ◽  
Induction Melting ◽  
Ductile Phase ◽  
Three Point Bending ◽  
Surface Profiling ◽  
Temperature Fracture

AbstractThe present paper describes ductile-phase toughening in V-V3Si in-situ composites that were produced by conventional arc melting (AM), cold-crucible induction melting (IM), and coldcrucible directional solidification (DS). Notched three-point bending tests were performed to determine the effects of synthesis method on the room temperature fracture toughness of eutectic compositions, which contain nearly equal volume fractions of V3Si and the V(Si) solid solution phase. Fracture toughness values ranged from 10 MPa√m for the AM eutectic to over 20 MPa√m for the IM and DS eutectic alloys. SEM fractography, fracture surface profiling, and chemical analyses were performed to correlate the toughness values with the microstructures and interstitial concentrations produced by the three synthesis methods.

Effect of Mo Addition on Microstructure and Properties of Nb/Nb5Si3 In-Situ Composite

2004 ◽  
Vol 449-452 ◽  
pp. 753-756 ◽  
Author(s):  
Wei Li ◽  
Hai Bo Yang ◽  
Ai Dang Shan ◽  
Jian Sheng Wu
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Metastable Phase ◽  
High Strength ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Ductile Phase ◽  
Temperature Fracture ◽  
The Stability

Nb/Nb5Si3 in-situ composites are very attractive structural materials for these materials perform a good balance in mechanical properties, including a high strength at high temperature (>1373K) and reasonably high fracture toughness at room temperature. Metastable phase Nb3Si plays an important role in the properties of Nb/Nb5Si3 composites by affecting microstructure and volume fracture of ductile phase. In this paper, Nb-10Si-xMo and Nb-18Si-xMo (x=0,5,15) are prepared by arc melting and annealed at 1473K for 100h. Single edge-notched bending (SENB) test was used to study the fracture toughness of Nb-Si-Mo alloys. The stability of metastable phase is analyzed by XRD. The room temperature fracture toughness of Nb-10Si is 10.47MPa(m)1/2 and higher than that of binary Nb-18Si alloys at near-eutectic compositions. The addition of Mo improves the fracture toughness of as cast Nb-Si alloys from 4.1 MPa(m)1/2 to 9.9MPa(m)1/2 at near-eutectic compositions and decreases it from 10.47 MPa(m)1/2 to 8.8MPa(m)1/2 at hypoeutectic compositions.

Nickel-Alumina Composites: In Situ Synthesis by a Displacement Reaction, and Mechanical Properties

1994 ◽  
Vol 365 ◽  
Author(s):  
Steven A. Jones ◽  
James M. Burlitch ◽  
Ersan Üstündag ◽  
Jeannie Yoo ◽  
Alan T. Zehnder
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Constants ◽  
High Performance ◽  
In Situ Synthesis ◽  
Displacement Reaction ◽  
Ductile Phase ◽  
Flexure Strength ◽  
Alumina Composites

ABSTRACTNickel-alumina composites have the potential to be high performance materials. Alumina, with its excellent oxidation resistance, combined with a ductile phase such as nickel may provide a tough material with a lower density and higher Young's modulus, overall, a higher specific modulus than typical Superalloys. Dense, interpenetrating Ni-Al2O3 composites were synthesized using a displacement reaction between NiO and aluminum. The resulting composites were characterized in terms of their mechanical properties such as hardness, flexure strength, fracture toughness and elastic constants. The synthesis, characterization, and mechanical properties, as well as the effect of the interpenetrating microstructure on the toughening mechanisms and other properties will be discussed.

Fracture Toughness of NiAl In-Situ Eutectic Composites.

1992 ◽  
Vol 273 ◽  
Author(s):  
F. E. Heredia ◽  
J. J. Valencia
Keyword(s):  
Fracture Toughness ◽  
Mechanical Tests ◽  
Layered Material ◽  
Induction Melting ◽  
Directionally Solidified ◽  
Ordered Intermetallic ◽  
Initiation Fracture Toughness ◽  
Resistance Curves ◽  
Intermetallic Compound Nial

ABSTRACTMechanical tests were performed on directionally solidified (DS) NiAl in-situ eutectic composites in order to evaluate the effect of ductile reinforcements on the fracture resistance of the B2 ordered intermetallic compound NiAl. Reinforcements consisted of i) Mo fibers, ii) Cr fibers, and iii) Cr(Mo) solid solution plates. Near stoichiometric NiAl ingots were prepared by induction melting as reference material to compare with the eutectic composites. Resistance curves were obtained for the NiAl/Mo fibrous eutectic alloy as well as for the NiAl/Cr(Mo) layered material. The initiation fracture toughness of the DS NiAl/Mo and NiAl/Cr(Mo) eutectic composites is larger than that of the stoichiometric NiAl, with the layered material. producing the better properties. The mechanisms for such increase in fracture toughness are discussed.

Microstructure and room temperature fracture toughness of Nbss/Nb5Si3 in situ composites

2001 ◽  
Vol 9 (9) ◽  
pp. 827-834 ◽  
Author(s):  
Won-Yong Kim ◽  
Hisao Tanaka ◽  
Akio Kasama ◽  
Shuji Hanada
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
In Situ Composites ◽  
Temperature Fracture

Effect of Carbon Addition on the Microstructure and Mechanical Properties of the In Situ Formed TiAl/Ti2AlC Composites

2011 ◽  
Vol 217-218 ◽  
pp. 680-683
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Yi Ping Gong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Synthesis Method ◽  
Elemental Powder ◽  
Hot Press ◽  
Carbon Addition ◽  
Rockwell Hardness ◽  
Powder Mixtures

TiAl/Ti2AlC composites were successfully fabricated by hot-press-assisted reactive synthesis method from elemental powder mixtures of Ti, Al and C. The effect of C addition on the microstructures and mechanical properties of TiAl/Ti2AlC composites was investigated in detail. The results show that the Rockwell hardness, flexural strength and fracture toughness of the composites are modified by incorporation of in situ formed Ti2AlC. When the C content was 0.44 wt %, the flexural strength and the fracture toughness reach the maximum values of 658.7 MPa and 10.03 MPa•m1/2, respectively. The reinforcing mechanism was also discussed.

Influence of Cr2O3 Addition on the Properties of TiAl Composites

2011 ◽  
Vol 230-232 ◽  
pp. 789-792
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Fang Ni Du
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Synthesis Method ◽  
Strengthening Mechanism ◽  
Reaction Synthesis ◽  
The Matrix ◽  
Method Effects ◽  
Particulate Reinforced

Using Ti, Al and Cr2O3 as starting materials, Al2O3 particulate reinforced TiAl composites have been fabricated by in-situ reaction synthesis method. Effects of the Cr2O3 addition on the microstructures and mechanical properties of the TiAl/Al2O3 composites were investigated in detail. The results show that the composites have a matrix of TiAl, Ti3Al, and minor Cr containing phases, and a second reinforcement Al2O3. The addition of Cr2O3 effectively refined the structure of the matrix, and as a result, the mechanical properties of TiAl composites are improved. At Cr2O3 7.36 wt%, the flexural strength and fracture toughness reach the maximum values of 634.62 MPa and 9.79 MPa·m1/2, which are increased by 80% and 30%, respectively. The strengthening mechanism is also discussed.

Combustion Synthesis of Si3N4/MoSi2 Composite

2010 ◽  
Vol 92 ◽  
pp. 41-45
Author(s):  
Jian Guang Xu ◽  
Shi Bo Guo ◽  
Jian Hui Yan ◽  
Da Gong Zhang
Keyword(s):  
Mechanical Properties ◽  
Combustion Synthesis ◽  
Room Temperature ◽  
Composite Powder ◽  
Synthesis Method ◽  
Monolithic Material ◽  
Temperature Fracture ◽  
Mosi2 Composite ◽  
Fractured Surface

Si3N4 particle reinforced MoSi2 composite powder has been successfully synthesized combustion synthesis method. XRD and SEM results showed that the combustion product was mainly composed by MoSi2 and Si3N4. The as-prepared Si3N4/MoSi2 composite powder has been pressureless sintered at 1600°C for 1h. The microstructure and mechanical properties of the composite were investigated. Relative densities of the monolithic material and composite were 92.2% and 89.6%, respectively. The composite has higher Vicker’s hardness and flexural strength than monolithic MoSi2. Especially the room-temperature fracture toughness of the composite is from 4.21MPa•m1/2 for MoSi2 to 7.25MPa•m1/2 for composite, increased by 72.2%, respectively. The morphology of fractured surface of composite revealed the mechanism of improving mechanical properties of MoSi2 matrix. The results of this work showed that in situ Si3N4/MoSi2 composite powder prepared by combustion synthesis could be successfully pressureless sintered and significant improvement of mechanical properties could be achieved.

Microstructures and Properties of Ds in-Situ Composites of Nb-Ti-Si Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
B. P. Bewlay ◽  
M. R. Jackson ◽  
W. J. Reeder ◽  
H. A. Lipsitt
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Fracture Toughness ◽  
Room Temperature ◽  
In Situ Composites ◽  
Environmental Resistance ◽  
High Temperature Mechanical Properties ◽  
Three Phase ◽  
Temperature Fracture

AbstractIn-situ composites based on binary Nb-Si alloys and consisting of a Nb solid solution with Nb3Si or Nb5Si3 have shown a promising combination of low temperature and high temperature mechanical properties. The environmental resistance and room temperature fracture toughness of these composites can be further enhanced by additions such as Ti, Hf, Cr, and Al. In the present study, ternary Nb-Ti-Si alloys were prepared by directional solidification to generate aligned two and three phase composites containing a Nb solid solution with Nb3Si and/or Nb5Si3. The present paper will describe microstructures, phase equilibria and fracture toughness of these composites. The improvement in the room temperature fracture toughness over binary Nb-Nb5Si3 composites is discussed.

Facet crystallography of fractured V(2.7 wt% Si) solid solution

1994 ◽  
Vol 52 ◽  
pp. 622-623
Author(s):  
J. A. Sutliff ◽  
B. P. Bewlay ◽  
G. A. Henshall ◽  
M. J. Strum
Keyword(s):  
Solid Solution ◽  
Morphological Structure ◽  
Crystallographic Analysis ◽  
Solid Solution Alloy ◽  
Solid Solution Phase ◽  
Ductile Phase ◽  
High Temperature Alloys ◽  
Sem Micrograph ◽  
Facet Surface

V-Si binary alloys have been investigated as model high temperature alloys. Alloys with compositions between ~4 and 11 wt% Si can be fabricated as in-situ composites composed of the intermetallic V3Si phase and the V(Si) solid solution phase with a eutectic temperature of ~1870°C. The V(Si) phase is thought to be a ductile phase which provides toughness to the composite. We have previously reported on the fracture toughness of V-Si alloys.In this paper we present results on the fracture surface fractography and fracture facet crystallography of an arc-melted V(2.7 wt% Si) solid solution alloy fractured in bending. Figure 1 is a low magnification SEM micrograph of the surface of one half of a fractured bend bar. Many macroscopically flat facets can be seen and those for which crystallographic analysis was done have been labeled. Actually, the macro-facet surface as seen at higher magnification exhibits significant morphological structure, as can be observed in Figure 2 which shows detail of the facet labeled k.

Evaluation of Mechanical Properties of Alumina Green Compact during Sintering at Relative Low Temperature

2005 ◽  
Vol 297-300 ◽  
pp. 945-950
Author(s):  
Shoichi Nambu ◽  
Manabu Enoki
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Complex Shape ◽  
Green Compact ◽  
Bending Test ◽  
Fracture Toughness Test ◽  
Three Point Bending ◽  
Temperature Fracture ◽  
The Relationship ◽  
Measured Strength

Recently, ceramics was used extensively as structural materials and ceramics components became larger and more complex. Fracture sometimes occurs during firing because of large and complex shape, and this fracture interrupts manufacturing process. The simulation of sintering has been studied to prevent this fracture. However, it was difficult to simulate fracture process because there was little data on strength of green compact. It is necessary to measure strength during sintering in order to perform a useful simulation. In this study, we measured strength of two kind of alumina green compact during sintering. Three point bending test at elevated temperature was performed and strength was estimated at each temperature. A model for strength at relative low temperature was also proposed using the temperature dependence of specific surface area. Furthermore, fracture toughness test was performed and the relationship between strength and fracture toughness was obtained. Strength at relative low temperature increased with temperature. Fracture toughness was proportional to strength at the temperature range where materials demonstrated brittle fracture manner. Strength of each alumina was analyzed using this model.

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