Fabrication of Nano-MgO Reinforced Fe-Cr-Ni Composites by Reactive Hot Pressing

2009 ◽  
Vol 620-622 ◽  
pp. 551-554 ◽  
Author(s):  
Chang Chen ◽  
Jian Feng Yang ◽  
Ji Qiang Gao ◽  
Cong Yang Chu
Keyword(s):  
Hot Pressing ◽  
Low Temperatures ◽  
Bending Strength ◽  
Exothermic Reaction ◽  
X Ray ◽  
Three Point Bending ◽  
Fine Grained ◽  
In Situ Formation ◽  
Reactive Hot Pressing

The self-propagating combustion reaction 0.741Mg + 0.247Fe2O3 + 0.188Ni + 0.318Cr → 0.741MgO + Fe0.494Ni0.188Cr0.318 was applied to prepare a nano-MgO reinforced Fe-Cr-Ni composite, by reactive hot pressing (RHP) under a condition of 700°C/30MPa/2h. The densification was enabled by the low temperatures produced by the exothermic reaction. According to TG-DTA and X-ray diffractometry (XRD), the highly-exothermic thermite reaction began at about 600°C and the in-situ formation of composites comprised predominantly of (FCC) Cr0.19Fe0.7Ni0.11, (FCC) Fe-Cr, (BCC) MgO and a small quantity of (BCC) MgFe2O4. The Vickers hardness was 3.67GPa, the three-point bending strength was 112.5±10MPa, and the fracture toughness was 3.28 MPa•m1/2. The microstructure of the composite was observed via scanning electron microscopy. This indicated that the distributions of in-situ-formed (BCC) MgO phases (~800 nanometers) were homogeneous into in a matrix of a fine-grained metallic alloy phases that gather together to form agglomerates in the composite.

Microstructure and Mechanical Property of Ti3AlC2/TiAl3 Composite Synthesized by Hot Pressing

2015 ◽  
Vol 816 ◽  
pp. 210-215
Author(s):  
Wei Ping Chen ◽  
Yong Zeng ◽  
Xiao Mei Li ◽  
Hua Qiang Xiao
Keyword(s):  
Hot Pressing ◽  
Bending Strength ◽  
Milling Process ◽  
Toughening Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
New Phase ◽  
Microstructure And Mechanical Property

Ti3AlC2/TiAl3 composite was successfully fabricated by ball milling and in-situ reaction/hot-pressing of Ti, Al and graphite powders mixture at 1200 °C and 30 MPa for 30 min. The phase composition and microstructure of the milled powders and synthesized composite were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the mechanical properties and the toughening mechanism of 20%vol Ti3AlC2/TiAl3 composite was also studied. The results show that no new phase is detected during 50 h of milling process. The in-situ synthesized samples are fully dense and composed of 72%vol TiAl3, 24%vol Ti3AlC2 and 4%vol Al2O3/TiC. The Vickers Hardness, three-point bending strength and fracture toughness of the composite is ~5.2 GPa, ~243 MPa and ~4.3 MPa/m1/2, respectively. Analysis of microstructure reveals that crack deflection, crack bridging and delamination of Ti3AlC2 are the main mechanism responsible for the toughening.

scholarly journals Microstructure and mechanical properties of Ti3(Al,Ga)C2/Al2O3 composites prepared by in situ reactive hot pressing

2020 ◽  
Vol 9 (6) ◽  
pp. 782-790
Author(s):  
Yuan Fang ◽  
Xiaohua Liu ◽  
Yuxia Feng ◽  
Jianfeng Zhu ◽  
Wei Jiang
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Raw Materials ◽  
Second Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Hot Pressing

AbstractIn this study, Ti3(Al,Ga)C2/Al2O3 composites were successfully synthesized by in situ hot pressing at 1350 °C for 2 h using Ti, Al, TiC, and Ga2O3 as raw materials. X-ray diffraction and scanning electron microscopy were used for characterizing the phase identities and microstructures of the sintered composites. The dependence of the Vickers hardness and flexural strength on the Al2O3 content was found to be in single-peak type. Ti3(Al0.6,Ga0.4)C2/10.3vol%Al2O3 composite exhibited significantly improved mechanical properties. Vickers hardness and flexural strength of the composite reached 6.58 GPa and 527.11 MPa, which were 40% and 74% higher than those of Ti3AlC2, respectively. Formation of solid solution and incorporation of second phase of Al2O3 resulted in the opposite influence on the fracture toughness. Finally, the hardening and strengthening mechanisms were discussed in detail.

Synthesis of Al2O3 Reinforced Ti3AlC2 In Situ Composites from Ti, Al, TiO2 and C

2011 ◽  
Vol 480-481 ◽  
pp. 523-526 ◽  
Author(s):  
Jian Feng Zhu ◽  
Lan Ye
Keyword(s):  
Hot Pressing ◽  
Hot Press ◽  
X Ray Diffraction ◽  
Pressing Method ◽  
X Ray ◽  
Tial Intermetallics ◽  
Three Stages ◽  
Hot Press Sintering ◽  
Reactive Hot Pressing

Al2O3 reinforced Ti3A1C2 in situ composites have been fabricated by reactive hot pressing method from the mixture of Ti, Al, TiO2 and C. The phase formation and transformation regularity of samples during the process of hot pressing were investigated in detail by X-ray diffraction (XRD). The microstructures of the synthesized samples were observed by scanning electron microscopy (SEM). The results show that the reactions of powder mixture during the hot press sintering could be divided into three stages: firstly, Ti reacted with Al to form TiAl intermetallics, and Ti reacted with C to form TiC, respectively; and then TiO2 was reduced by Al to form Al2O3, TiAl intermetallics reacted with TiC to form Ti2A1C; finally Ti3A1C2 was formed through the reaction between Ti2A1C and TiC.

scholarly journals In Situ Coherent X-ray Diffraction during Three-Point Bending of a Au Nanowire: Visualization and Quantification

2018 ◽  
Vol 2 (4) ◽  
pp. 24 ◽  
Author(s):  
Anton Davydok ◽  
Thomas Cornelius ◽  
Zhe Ren ◽  
Cedric Leclere ◽  
Gilbert Chahine ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Reciprocal Space ◽  
X Ray Diffraction ◽  
Complex Deformation ◽  
X Ray ◽  
Three Point Bending ◽  
Atomic Force ◽  
Au Nanowire ◽  
Before And After

The three-point bending behavior of a single Au nanowire deformed by an atomic force microscope was monitored by coherent X-ray diffraction using a sub-micrometer sized hard X-ray beam. Three-dimensional reciprocal-space maps were recorded before and after deformation by standard rocking curves and were measured by scanning the energy of the incident X-ray beam during deformation at different loading stages. The mechanical behavior of the nanowire was visualized in reciprocal space and a complex deformation mechanism is described. In addition to the expected bending of the nanowire, torsion was detected. Bending and torsion angles were quantified from the high-resolution diffraction data.

Reactive hot pressing of aluminum matrix composites

1999 ◽  
Vol 14 (11) ◽  
pp. 4246-4250
Author(s):  
H. J. Brinkman ◽  
J. Duszczyk ◽  
L. Katgerman
Keyword(s):  
Hot Pressing ◽  
Adverse Reactions ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Processing Step ◽  
Exothermic Process ◽  
Composite Product ◽  
Reactive Hot Pressing

A method is described for the production of dense aluminum matrix composites from elemental powders in one processing step by reactive hot pressing (RHP). It encompasses both the exothermic conversion of reactants to composite product and the following hot compaction of the porous composite product. The RHP method described in this paper takes into account the gas evolution accompanying the exothermic process, ensures complete conversion of reactants, and avoids adverse reactions between aluminum matrix and graphite tooling material. In situ sample temperature measurements enable proper process control, in particular the timing of the full densification step of the hot reaction product.

scholarly journals CAAC Boranes. Synthesis and characterization of cyclic (alkyl) (amino) carbene borane complexes from BF3 and BH3

2010 ◽  
Vol 6 ◽  
pp. 709-712 ◽  
Author(s):  
Julien Monot ◽  
Louis Fensterbank ◽  
Max Malacria ◽  
Emmanuel Lacôte ◽  
Steven J Geib ◽  
...  
Keyword(s):  
Silica Gel ◽  
Synthesis And Characterization ◽  
Gel Chromatography ◽  
Nmr Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
In Situ Formation ◽  
Silica Gel Chromatography

In situ formation of two cyclic (alkyl) (amino) carbenes (CAACs) followed by addition of BF3•Et2O provided the first two examples of CAAC–BF3 complexes: 1-(2,6-diisopropylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene trifluoroborane, and 2-(2,6-diisopropylphenyl)-3,3-dimethyl-2-azaspiro[4.5]decan-1-ylidene trifluoroborane. These CAAC–BF3 complexes are robust compounds that are stable to ambient laboratory conditions and silica gel chromatography. They were characterized by spectroscopy and X-ray crystallography. In contrast, a CAAC complex with borane (BH3) was readily formed in situ according to 1H and 11B NMR analysis, but did not survive the workup conditions. These results set the stage for further studies of the chemistry of CAAC boranes.

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