Large-Scale (Ti,Cr)B2-Cu Composite by Combustion Synthesis

2007 ◽  
Vol 280-283 ◽  
pp. 1441-1444 ◽  
Author(s):  
Qiang Xu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Xiao Dong He

Large-scale (Ti,Cr)B2-Cu composite from Ti, Cr, B and Cu powders was produced by combining combustion synthesis with Pseudo Hot Isostatic Pressing. The diameter of the synthesized product is 240 millimeter. The product was identified using X-ray diffraction and the result showed that only (Ti,Cr)B2 and Cu phases, without other phases, existed in the product. The analysis of the microstructure indicated that the skeletal structure had been formed in the (Ti,Cr)B2 solid solution phase. Fine (Ti,Cr)B2 reinforcement grew in near equivalent axis-like shape and some sintering neckings were found between the solid solution phases. The relative density of the synthesized product was 93.6% because the skeletal structure baffled the densification of the composite. The bending strength and fracture toughness of the product were 476 MPa and 6.8 MPa·m1/2 respectively.

2013 ◽  
Vol 747-748 ◽  
pp. 765-771 ◽  
Author(s):  
Jian Sheng Yao ◽  
Ding Zhong Tang ◽  
Xiao Guang Liu ◽  
Cheng Bo Xiao ◽  
Xin Li ◽  
...  

The interfacial reactions between ceramic moulds and DZ417G and DZ125 superalloys were investigated. The microstructure and composition of the interface region were observed by optical microscope, X-ray diffraction and scanning electron microscope with energy dispersive spectroscopy. The results showed that (Al1-xCrx)2O3solid solution phase with pink color was formed from the dissolution of Cr2O3and Al2O3and vapour phase, which was transferred to the reaction surfaces. The reaction layer thicknesses of DZ417G and DZ125 alloys were about in the range of 40-50μm. The interface reaction product between DZ417G alloy and ceramic mould was TiO2and the product between DZ125 alloy and ceramic mould was HfO2.


Author(s):  
Xuehong Cui ◽  
Jinming Zhu ◽  
Ketong Luo ◽  
Jianlie Liang

Abstract Phase relationships in the Ce-Nd-B ternary system at 773 K were investigated by means of X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy techniques. Six borides, i. e. CeB4, CeB6, NdB4, NdB6, NdB66 and Nd2B5 are confirmed in this work. No ternary compound was observed. CeB4 and NdB4 were discovered to form the continuous solid solution phase (Ce,Nd)B4, CeB6 and NdB6 also form the solid solution phase (Ce,Nd)B6. The maximum solid solubility of Ce in (Ce,Nd)2B5 phase is 46.5 at.%. The isothermal section of the Ce-Nd-B ternary system at 773 K consists of 3 three-phase regions, 7 two-phase regions and 7 single- phase regions.


2008 ◽  
Vol 104 (11) ◽  
pp. 113527 ◽  
Author(s):  
L. Alves ◽  
T. P. A. Hase ◽  
M. R. C. Hunt ◽  
A. C. Brieva ◽  
L. Šiller

1987 ◽  
Vol 99 ◽  
Author(s):  
C. Y. Yang ◽  
S. M. Heald ◽  
J. J. Reilly ◽  
M. Suenaga

ABSTRACTWe have examined the role of H on the superconductivity properties, the atomic structure, and the electronic state in the HxYBa2Cu3O7. The hydrogen solid solution phase (up to ×≃O.2) exhibits a superconducting transition at 94 K, which was usually slightly higher than the starting oxide (YBa2Cu3O7, while the hydride phases (H rich) are not superconducting. Infrared (IR), x-ray diffraction, and x-ray absorption spectroscopy (XAS) measurements indicate that H is located interstitially only near Cu sites.


Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1620
Author(s):  
Xiaomin Yuan ◽  
Haonan Zhu ◽  
Huiling Ji ◽  
Yiwei Zhang

Carbon nanotubes (CNTs), dispersed in absolute ethanol, were evenly mixed into Ti/MgH2 powders by wet milling. Then, we applied the vacuum hot-pressed sinteringmethod to the CNTs/TiMg composite materials. An optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and a field emission scanning electron microscope (FESEM) were used for the microstructure observation and phase analysis of samples. The mechanical properties were measured via the micro-vickers hardness. The results show that the main phases in the composites were Ti, Mg and C. Meanwhile, a small amount of Ti-Mg solid solution phase was also found. The cross-section morphology of the composites shows that the melted magnesium fills the grain interface during extrusion and that the composites have a better compactness.The microstructures of the composites have been greatly refined as the CNT contents increased. The structure of the composites was further refined when 0.5 wt.% CNTs were added. The fracture surface is obviously a ductile fracture. The microhardness increases obviously with the CNT content increasing. When the content of the CNTs is 1.0 wt.%, the microhardness of the composites reaches 232 HV, which is 24% higher than that of the matrix.


Author(s):  
Z.T. Zhang ◽  
H.P. Nie ◽  
K. Yan

Sb distribution in the phases of SiO2 saturated Sb-Fe-O-SiO2-CaO system has been determined for the first time through high-temperature experiment and quenching techniques, followed by Electron probe X-ray microanalysis(EPMA) in air(Ptot= 1 atm, PO2= 0.21 atm). The phases were quantified in the temperature range of 900?C-1200?C and the effects of Fe/SiO2(mass fraction) and CaO/SiO2(mass fraction) on Sb2O3 content in the Sb-Fe-O-SiO2-CaO system were investigated at 1200?C. The results indicate that the Sb-containing phase primarily existed in the solid solution phase at 1200?C. With the increase of temperature from 1100?C to 1200?C, the Sb2O3 content in the solid solution phase increased drastically from 7.52 wt% to 17.36 wt%. Lowering the values of CaO/SiO2 and Fe/SiO2 in the smelting process effectively reduced Sb2O3 content in the slag. The verification experiment results suggest that the antimony content in slag was 0.57 wt%, the crude antimony yield rate was lower than 4%,and the crude antimony grade was beyond 94 wt%, which can achieve the reduction of antimony content in the slag.


2014 ◽  
Vol 488-489 ◽  
pp. 9-13
Author(s):  
Guang Xian ◽  
Hai Bo Zhao ◽  
Hong Yuan Fan ◽  
Hao Du

ZrAlYN films were prepared by magnetron sputtering at various N2/Ar flow ratio. The structure, composition and thermal properties were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectrum. The results show that the deposited ZrAlN and ZrAlYN films possessed a single NaCl-type solid solution phase. The ZrAlN film was (200) strongly predominated. The (111) peak was prominently increased in ZrAlYN films and thus the preferred orientation changed to (111) and (200) co-predomination. The crystallinity of ZrAlYN films was gradually degraded with enhanced N2/Ar flow ratio. Both ZrAlN and ZrAlYN films were exhibited a featureless fracture microstructure. The thickness of ZrAlYN films was consistently reduced due to more nitride produced on the surface of targets at higher N2/Ar flow ratio. The ZrAlYN films deposited at 1:5 N2/Ar flow ratio was proved to be the best oxidation resistance under annealing at 1000°C for 2h in air. As N2/Ar flow ratio increased, the oxidation resistance of films was inversely deteriorated due to the decreased yttrium content in films.


2009 ◽  
Vol 24 (8) ◽  
pp. 2528-2535 ◽  
Author(s):  
Yuelei Bai ◽  
Xiaodong He ◽  
Yibin Li ◽  
Chuncheng Zhu ◽  
Sam Zhang

In this study, the dense polycrystalline Ti2AlC was synthesized by self-propagating high-temperature combustion synthesis with the pseudo–hot isostatic pressing process (SHS/PHIP). The resultant phase purity is highly dependent on the mol ratio of raw powders. The Ti2AlC was densified by applying pressure after the SHS reaction. The resultant sample mainly contains typical plate-like nonstoichiometric Ti2AlCx (x = 0.69) with grain size of ∼6 µm. The sample shows the Vickers hardness of 5.5 GPa, highest flexural strength of 431 MPa, compressive strength of 1033 MPa, and fracture toughness of 6.5 MPa·m1/2. No indentation cracks in Ti2AlCx were observed, indicative of a damage material nature. The reaction mechanism for the formation of SHS/PHIP-derived Ti2AlC is also discussed based on differential thermal analysis and x-ray diffraction results.


2004 ◽  
Vol 842 ◽  
Author(s):  
Nobuaki Sekido ◽  
Ridwan Sakidja ◽  
John H. Perepezko

ABSTRACTUpon annealing an as-cast Mo-10Si-20B alloy at high temperatures, a Mo solid solution phase precipitates within a supersaturated Mo5SiB2 phase. The precipitation behavior of the Mo solid solution was investigated by means of transmission electron microscopy and X-ray diffractometry. It is found that the Mo5SiB2 phase in a Mo-10Si-20B alloy contains a significant amount of structural vacancies in the as-cast state. The excess vacancies are removed to form dislocations during annealing, which provides the heterogeneous nucleation sites for the (Mo) precipitates.


Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.


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