EFFECT OF Si ON MICROSTRUCTURE AND FRACTURE TOUGHNESS OF DIRECTIONALLY SOLIDIFIED Nb SILICIDE ALLOYS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2964-2969 ◽  
Author(s):  
MEILING WU ◽  
YUYE WANG ◽  
SHUSUO LI ◽  
LIWU JIANG ◽  
YAFANG HAN
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
Micro Cracks ◽  
Temperature Fracture ◽  
Si Content ◽  
Energy Disperse Spectroscopy

Nb - xSi ( x =3,9,16)-22 Ti -3 Cr -3 Al -2 Hf (at.%) have been successfully prepared by directional solidification in an optical floating zone furnace. Microstructure analysis and phases identification of the alloys were examined by X-ray diffraction (XRD), Electro Probe Micro Analyzer (EPMA) and Energy Disperse Spectroscopy (EDS). Fracture toughness specimens without pre-crack were prepared, room temperature fracture toughness of alloys was tested by three-point bending method, and fracture mechanism was studied. The results showed that with increasing Si content, Nb 5 Si 3 phase gradually increased and the phase transformed from γ- Nb 5 Si 3 to the stable α- Nb 5 Si 3 phase and β- Nb 5 Si 3 phase. There appeared the Ti -rich Nb 5 Si 3 phase when the Si content is 16 at%. In addition, more micro-cracks generated in the Ti -rich Nb 5 Si 3 phase, which seriously affected room temperature fracture toughness of the alloys.

Effect of Trace Strontium Addition on Microstructure and Room Temperature Fracture Toughness of Nb-12Si-22Ti Alloys

2016 ◽  
Vol 849 ◽  
pp. 603-608 ◽  
Author(s):  
Mei Ling Wu ◽  
Feng Wei Guo ◽  
Ming Li ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Fracture ◽  
The Relationship ◽  
Scanning Electron

The effect of strontium (Sr) addition (0.2 at.%) on the microstructure and mechanical properties of Nb-12Si-22Ti alloys were studied. Microstructure of the alloys was observed by scanning electron microscope, and their phase compositions were analyzed with X-ray diffraction and Electro-Probe Microanalyzer. The room temperature fracture toughness was measured. The results indicated that the phases of Nbss and Nb3Si were presented in Nb-12Si-22Ti alloys. However, with the Al and Sr addition, the alloys were composed of Nbss and β-Nb5Si3. Compared with the Nb-12Si-22Ti alloys, the value of room temperature fracture toughness increased about 46% and 73% with the addition of Al and Sr alloy, respectively. The relationship between the microstructure and the mechanical properties was discussed.

Mechanochemical reactions in the system FeTiO3–Si

1998 ◽  
Vol 13 (12) ◽  
pp. 3499-3503
Author(s):  
Ying Chen ◽  
J. S. Williams
Keyword(s):  
Room Temperature ◽  
Reaction Rate ◽  
Thermal Analyses ◽  
Mechanochemical Reaction ◽  
X Ray Diffraction ◽  
Reaction Stage ◽  
X Ray ◽  
Powder Composition ◽  
Si Content ◽  
Mechanochemical Reactions

Mechanochemical reactions in the system FeTiO3 –Si have been investigated as functions of the powder composition and milling conditions, using x-ray diffraction and thermal analyses. Reduction reactions of FeTiO3 by Si were observed during room-temperature milling with the formation of α–Fe, amorphous SiOx, nanocrystalline TiO2, or intermetallic compounds, depending on the Si content. The mechanochemical reaction process consists of a mechanical activation stage and a reaction stage. Higher milling intensity leads to a shorter activation step and a higher reaction rate.

Processing and Mechanical Properties of RuAl-Based Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1469-1474 ◽  
Author(s):  
T.D. Reynolds ◽  
M. Acosta ◽  
David R. Johnson
Keyword(s):  
Fracture Toughness ◽  
Cyclic Oxidation ◽  
Room Temperature ◽  
Single Phase ◽  
Tensile Ductility ◽  
Tensile Behavior ◽  
Directionally Solidified ◽  
Two Phase ◽  
Heat Treated ◽  
Temperature Fracture

Alloys of Ru-Al-Cr with compositions between Ru-10Al-35Cr and Ru-3Al-39Cr (at.%) were directionally solidified and heat treated to produce single phase hcp-Ru(Cr,Al) and two phase B2-hcp microstructures. The room temperature fracture toughness, tensile behavior, and cyclic oxidation behavior at 1100°C were investigated and compared to previous results measured from RuAl and Ru-Al-Mo alloys. For microstructures consisting of a Ru(Cr,Al) matrix with fine RuAl precipitate, a good room temperature fracture toughness, tensile ductility, and oxidation resistance at 1100°C were measured.

X-Ray Diffraction Observation of Fracture Surfaces of Ductile Cast Iron

1982 ◽  
Vol 26 ◽  
pp. 291-298 ◽  
Author(s):  
Zenjiro Yajima ◽  
Yukio Hirose ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Cast Iron ◽  
Compact Tension ◽  
Ductile Cast Iron ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
Fracture Surfaces ◽  
Machine Parts

X-ray diffraction observation of metal fractures provides fracture analysists with useful information on the mechanisms and mechanical conditions of fracturing. This method is called “X-ray fractography” and has been developed especially in Japan as a new engineering tool for fracture analysis.In the present paper, X-ray fractography is applied to fracture surfaces of ductile cast iron (JIS FCD 60) which are widely used as machine parts. The fracture toughness tests were conducted at ambient and low temperatures by using compact tension (CT) specimens with blunt notches and three-point bending (TPB) specimens with fatigue pre-cracks. The line broadening of X-ray diffraction profiles was measured on and beneath fracture surfaces of fracture toughness specimens.

Effect of TiC Content on Fracture Toughness of TiC-Ti5Si3 Composites

2007 ◽  
Vol 280-283 ◽  
pp. 1885-1888 ◽  
Author(s):  
Lian Jun Wang ◽  
Wan Jiang ◽  
Sheng Qiang Bai ◽  
Li Dong Chen
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Reactive Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Indentation Tests ◽  
Spark Plasma ◽  
Scanning Electron

In-situ toughened TiC-Ti5Si3 composites were fabricated using reactive sintering of Ti and SiC via spark plasma sintering (SPS). The focus of this work on the content of TiC in final composites was different. The phase constituents and microstructures of the samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Fracture toughness at room temperature was also measured by indentation tests. The results showed that the corporation of TiC greatly enhances the fracture toughness of TiC-Ti5Si3 composites.

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