Synthesis and Properties of In-Situ MoSi2/SiC Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
S. Jayashankar ◽  
S.E. Riddle ◽  
M. J. Kaufman
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Room Temperature ◽  
Indentation Fracture ◽  
Processing Scheme ◽  
Indentation Fracture Toughness ◽  
Novel Processing ◽  
Sic Composites

AbstractCompositionally-tailored, silica-free, MoSi2/SiC composites with SiC content ranging from 0 to 40 percent were synthesized through a novel processing scheme involving mechanical alloying and in-situ reactions for the formation of the reinforcement. Room temperature indentation fracture toughness and hardness measurements were obtained from these silica-free composites and were compared with values obtained from silica-containing, conventionally-processed MoSi2/SiC composites.

Microstructure and Mechanical Properties of Sm1-xSrxCo0.2Fe0.8O3

2000 ◽  
Vol 15 (7) ◽  
pp. 1505-1513 ◽  
Author(s):  
Y-S. Chou ◽  
J. W. Stevenson ◽  
T. R. Armstrong ◽  
J. S. Hardy ◽  
K. Hasinska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Indentation Fracture ◽  
Flexure Strength ◽  
Indentation Toughness ◽  
Indentation Fracture Toughness ◽  
Microhardness Indentation ◽  
Biaxial Flexure

The room temperature mechanical properties of a mixed conducting perovskite Sm1?xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phase, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of elastic modulus, microhardness, indentation fracture toughness, and biaxial flexure strength were measured. Young's modulus of 180–193 GPa and shear modulus of 70–75 GPa were determined. The biaxial flexure strength was found to decrease with increasing Sr content from ∼70 to ∼20 MPa. The drop in strength was due to the occurrence of extensive cracking. Indentation toughness showed a similar trend to the strength in that it decreased with increasing Sr content from ∼1.1 to ∼0.7 MPa m1/2. In addition, fractography was used to characterize the fracture behavior in these materials.

Comparison of R-Curve Behavior of Si3N4 Measured by Indentation Method and Single-Edge V-Notched Beam Technique (SEVNB)

2009 ◽  
Vol 409 ◽  
pp. 308-312
Author(s):  
Jana Špaková ◽  
Ján Dusza
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Single Edge ◽  
Indentation Fracture ◽  
Indentation Method ◽  
Indentation Toughness ◽  
Indentation Fracture Toughness ◽  
Beam Technique

Study compare R-curve behaviour of silicon nitride obtained using Vickers indented beam specimens and single edge V-notched beam (SEVNB). R-curve measurement realized by Vickers indented beam was reported by Krause. Crack growth using single edge V-notched beam was observed in situ. The indentation experiments, in comparison with SEVNB method revealed higher R-curve values (KR=3.3 – 4.8 MPa.m1/2). The discrepancy in the R-curve results is attributed to inaccuracy related to the determination of indentation toughness. The indentation fracture toughness may include the aspects of crack opening behaviour, residual indentation stress intensity.

Enhanced thermoelectric and mechanical properties of p-type skutterudites with in situ formed Fe3Si nanoprecipitate

2017 ◽  
Vol 4 (10) ◽  
pp. 1697-1703 ◽  
Author(s):  
Shengyuan Peng ◽  
Jianhui Sun ◽  
Bo Cui ◽  
Xianfu Meng ◽  
Dandan Qin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermoelectric Properties ◽  
Indentation Fracture ◽  
Indentation Fracture Toughness ◽  
P Type

Hardness and indentation fracture toughness of La0.8Ti0.1Ga0.1Fe3CoSb12can be improved byin situformed Fe3Si, without sacrificing thermoelectric properties.

Preparation of SiC/MoSi2 Composites by Mechanical Alloying and its Fracture Properties

2007 ◽  
Vol 539-543 ◽  
pp. 1047-1052 ◽  
Author(s):  
Hsin Ming Wu ◽  
Chia Jung Hu ◽  
Ya Hui Chou
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Vacuum Furnace ◽  
Indentation Fracture ◽  
Composite Powders ◽  
Fracture Properties ◽  
Sic Particles ◽  
Indentation Fracture Toughness ◽  
Milled Powders

Ball milling was utilized to make composite powders from either elemental Mo, Si, C powders or compound MoSi2 and SiC powders. The milled powders were hot-pressed in a vacuum furnace to produce 10 to 30 vol.% SiC-reinforced MoSi2 composites. The influence of microstructure on the indentation fracture toughness of the fabricated SiC/MoSi2 composites was investigated. The SiC particles present in the consolidated compound composite are larger than those in the elemental composite while the pores observed in the former composite are fewer than in the latter. The overall values of fracture toughness measured on the compound composites are higher than those of elemental composites. The major reason for the greater toughness of compound composites is due to the larger SiC particles and fewer pores in these materials.

Microstructural Evolution in Compositionally Tailored MoSi2/SiC Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
S.E. Riddle ◽  
S. Jayashankar ◽  
M.J. Kaufman
Keyword(s):  
Mechanical Alloying ◽  
Microstructural Evolution ◽  
Processing Parameters ◽  
Processing Temperature ◽  
Processing Scheme ◽  
Powder Composition ◽  
Important Processing ◽  
Novel Processing ◽  
Sic Composites ◽  
Carbide Content

AbstractCompositionally tailored MoSi2/SiC composites with silicon carbide content ranging from 0 to 60 volume percent were synthesized through a novel processing scheme involving the mechanical alloying of elemental molybdenum, silicon, and carbon. The effects of important processing parameters such as the nominal powder composition and the processing temperature on the microstructural evolution during mechanical alloying and subsequent heating are described based on the results obtained from DTA and XRD.

A Transparent and Tough β-Si3N4 Ceramic with a Whiskery Microstructure

2015 ◽  
Vol 655 ◽  
pp. 1-5
Author(s):  
Peng Xi Li ◽  
Hong Qiang Wang ◽  
Liu Cheng Gui ◽  
Jun Li ◽  
Hai Long Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Amorphous Phase ◽  
Hot Pressing ◽  
High Density ◽  
Indentation Fracture ◽  
Indentation Fracture Toughness ◽  
Resultant Material

The transparent β-Si3N4ceramic with a whisker-like microstructure was prepared by hot-pressing at 2000 °C for 26 h, with MgSiN2as an additive. The resultant material achieves the maximum transmittance of 70 % at the wavelength of about 2.5 μm and the transmittance value keeps higher than 60 % in the range of 700-4500 nm wavelength, which is attributed to the very small amount of the intergranular amorphous phase along with high density. The present transparent β-Si3N4ceramic exhibits an indentation fracture toughness of 7.2±0.3 MPa m1/2.

Pulsed Electric Current Sintered Cr2O3-rGO Composites

2016 ◽  
Vol 721 ◽  
pp. 419-424
Author(s):  
M. Erkin Cura ◽  
Vivek Kumar Singh ◽  
Panu Viitaharju ◽  
Joonas Lehtonen ◽  
Simo Pekka Hannula
Keyword(s):  
Fracture Toughness ◽  
Graphene Oxide ◽  
Electric Current ◽  
Chromium Oxide ◽  
High Hardness ◽  
High Wear Resistance ◽  
Carbide Formation ◽  
Indentation Fracture ◽  
Pulsed Electric Current ◽  
Indentation Fracture Toughness

Chromium oxide is a promising material for applications where excellent corrosion resistance, high hardness, and high wear resistance are needed. However, its use is limited because of low fracture toughness. Improvement of fracture toughness of chromium oxide while maintaining its afore mentioned key properties is therefore of high interest. In this communication we study the possibility of increasing the toughness of pulsed electric current sintered (PECS) chromium oxide by the addition of graphene oxide (GO). The indentation fracture toughness was improved markedly with the addition of graphene oxide. Materials prepared by direct chemical homogenization had better fracture toughness. In composites with 10 vol.% GO piling of thin graphene oxide layers resulted in the formation of graphite layers between Cr2O3 and in carbide formation, which were observed to be the main reasons for the degradation of the mechanical properties. The distribution of graphene oxide was more homogeneous, when the GO amount was 0.1 vol.% and the formation of graphitic layers were avoided due to lesser amount of GO as well as ultrasonic treatment following the ball milling.

Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 255-260 ◽  
Author(s):  
G. Zhang ◽  
L. Hu ◽  
W. Hu ◽  
G. Gottstein ◽  
S. Bogner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Creep Resistance ◽  
Room Temperature ◽  
Growth Direction ◽  
Nominal Composition ◽  
Potential Candidate ◽  
In Situ Composites

ABSTRACTMo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

Structure and Properties of Single Crystal Al2O3 Implanted with Chromium and Zirconium

1981 ◽  
Vol 7 ◽  
Author(s):  
C. J. Mchargue ◽  
H. Naramoto ◽  
B. R. Appleton ◽  
C. W. White ◽  
J. M. Williams
Keyword(s):  
Fracture Toughness ◽  
Single Crystal ◽  
Single Crystals ◽  
Solid Solutions ◽  
Rutherford Backscattering ◽  
Structure And Properties ◽  
Indentation Fracture ◽  
Surface Layers ◽  
Indentation Fracture Toughness

ABSTRACTSingle crystals of Al2O3 were implanted with chromium and zirconium to fluences of 1 × 1016 to 1 × 1017 ions cm−2. Rutherford backscattering-channeling studies showed the surface layers to be damaged but crystalline with the implanted ions randomly distributed. The microhardness and indentation fracture toughness were higher for the random solutions than for conventionally formed solid solutions. Changes in structure and properties caused by annealing in air at temperatures up to 1800°C were studied.

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