Synthesis of Al2O3-Ni3Al Cermets by Room-Temperature Ball Milling of Al, Ni and Al2O3 Mixtures

2006 ◽  
Vol 509 ◽  
pp. 123-128
Author(s):  
Enrique Rocha-Rangel ◽  
M.S. Moreno-Guerrero ◽  
A. Velásquez-Naranjo ◽  
Elizabeth Refugio-García
Keyword(s):  
Ball Milling ◽  
Room Temperature ◽  
Exothermic Reaction ◽  
Inert Atmosphere ◽  
Reactive Sintering ◽  
Sintering Process ◽  
Interpenetrating Networks ◽  
Heat Treated ◽  
Ni3al Intermetallic

The synthesis of Al2O3-Ni3Al cermets with interpenetrating networks has been performed via a pressureless reactive sintering process. The synthesis has been induced by means of a solidstate reaction of Al + Ni + Al2O3 powders under intensive ball milling. The mixtures have been heat treated in an inert atmosphere (N2) in order to control the exothermic reaction between Ni and Al, with special care at temperatures near the melting point of Al. Dense and homogeneous microstructures have been obtained, composed by a matrix of Al2O3 reinforced with a Ni3Al intermetallic. Thermodynamic calculations indicate that such a cermet can be fabricated by in situ reaction synthesis. This suggests that a pressureless reaction sintering process may be a general route to synthesizing cermets with the prospect for the production of cermets with interpenetrating networks.

Reaction sintering of alumina-aluminide alloys (3A)

1996 ◽  
Vol 11 (11) ◽  
pp. 2884-2888 ◽  
Author(s):  
N. Claussen ◽  
D. E. Garcia ◽  
R. Janssen
Keyword(s):  
Phase Composition ◽  
Melting Point ◽  
Metal Oxide ◽  
Inert Atmosphere ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Interpenetrating Networks ◽  
Exothermic Reactions ◽  
Heat Treated ◽  
Wide Range

A novel pressureless reaction sintering process is presented for the fabrication of Al2O3-aluminide alloys (3A). Compacts of intensively milled metal oxide-aluminum mixtures are heat-treated in vacuum or inert atmosphere such that the exothermic reactions take place in a controlled manner essentially at temperatures below the melting point of Al. Dense, homogeneous microstructures were obtained with a variety of Al2O3-matrix systems with interpenetrating networks of aluminides of Ti, Fe, Nb, Mo, Zr, Ni, etc. By adding modifiers in the form of oxides or metals, volume and phase composition as well as properties can be tailored in a wide range.

Nanostructure formation mechanism during in-situ consolidation of copper by room-temperature ball milling

2015 ◽  
Vol 65 ◽  
pp. 1083-1090 ◽  
Author(s):  
M. Samadi Khoshkhoo ◽  
S. Scudino ◽  
T. Gemming ◽  
J. Thomas ◽  
J. Freudenberger ◽  
...  
Keyword(s):  
Ball Milling ◽  
Formation Mechanism ◽  
Room Temperature ◽  
Nanostructure Formation

Processing and Properties of Nb5Si3/Nb Laminates

1994 ◽  
Vol 350 ◽  
Author(s):  
John Short ◽  
Jan Kajuch ◽  
John J. Lewandowski
Keyword(s):  
Solid Solution ◽  
Mechanical Alloying ◽  
Hot Pressing ◽  
Reactive Sintering ◽  
Mechanically Alloyed ◽  
Pure Niobium ◽  
Commercially Pure ◽  
Heat Treated ◽  
Bend Tests

AbstractMechanical alloying(MA) and Reactive Sintering(RS) techniques were successfully used to produce Nb5Si3. Model laminates of mechanically alloyed Nb5Si3 and commercially pure niobium were prepared via vacuum hot pressing. Tensile properties for the as-received, vacuum heat treated and niobium with a solid solution of silicon were obtained at 298K and 77K. 298K bend tests were conducted in an in situ deformation stage in a SEM. 77K bend tests were also conducted. Toughness values are correlated to the ligament properties and effect of constraint.

Properties of Reactively Synthesized Titanium Aluminides

1994 ◽  
Vol 364 ◽  
Author(s):  
D. E. Alman ◽  
J. A. Hawk ◽  
R. D. Wilson
Keyword(s):  
Tensile Properties ◽  
Titanium Aluminides ◽  
Reactive Sintering ◽  
Composite Sheet ◽  
Reactive Synthesis ◽  
Heat Treated ◽  
Complex Shapes ◽  
Kirkendall Porosity ◽  
Hot Hardness

AbstractReactive synthesis directly forms compounds from their elemental constituents. In this U.S. Bureau of Mines study the microstructure, hot-hardness and tensile properties of alloys and composites based on TiAl and Ti2AlNb were studied. Ti2AlNb sheets were processed from elemental Ti, Al and Nb foils. The elemental foils were consumed during processing, leaving a microstructure consisting of three phases: O (orthorhombic Ti2AlNb), B2 (ordered cubic Ti), and α2 (Ti3Al). The composite sheet structures were heat-treated to produce a microstructure consisting of O lathes in a B2 matrix. A significant advantage of reactive synthesis is the ease of formation of complex shapes prior to synthesis of the aluminide. TiAl-based alloys and in situ TiAl/boride and TiAl/Ti5Si3 composites were produced from elemental mixtures of Ti and Al with either additions of B or Si powders. The hot-hardness and tensile properties of these alloys and composites are reported. The Kirkendall porosity associated with reactive sintering of TiAl can be eliminated by simultaneously reactive sintering TiAl and Ti5Si3.

Preparation and Characterization of SiC/MoSi2 Composites from Powder Resulting from a Mechanical-Assistant Combustion Synthesis Method

2010 ◽  
Vol 105-106 ◽  
pp. 70-74
Author(s):  
Jian Guang Xu ◽  
Hui Qiang Li ◽  
Hou An Zhang
Keyword(s):  
Mechanical Properties ◽  
Cyclic Oxidation ◽  
Room Temperature ◽  
Synthesis Method ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Oxidation Properties ◽  
Mosi2 Composite

SiC reinforced MoSi2 composites have been successfully prepared by pressureless sintering from mechanical-assistant combustion synthesized powders. The sintering temperatures and holding time were 1500°C~1650°C at a heating rate of 10K/min and 1 hour, respectively. The microstructure and mechanical properties of the as-sintered composites were investigated. SEM micrographs of SiC/MoSi2 composites showed that SiC particles were homogeneously distributed in MoSi2 matrix. The Vickers hardness, flexural strength and fracture toughness of the SiC/MoSi2 composites were up to 15.50GPa, 468.7MPa and 9.35MPa•m1/2, respectively. The morphologies of fractured surface of the composites revealed the mechanism to improve mechanical properties of MoSi2 matrix. At last, the cyclic oxidation behavior of the composites was discussed. The results of this work showed that in situ SiC/MoSi2 composite powder prepared by MASHS technique could be successfully sintered via pressureless sintering process and significant improvement of room temperature mechanical and anti-oxidation properties could be achieved.

Synthesis of SiCW/(Mo,W)Si2 Composite by the "Chemical Oven" Self-Propagating Combustion Method

2008 ◽  
Vol 368-372 ◽  
pp. 951-954 ◽  
Author(s):  
Jian Guang Xu ◽  
Hou An Zhang ◽  
Guo Jian Jiang ◽  
Wen Lan Li
Keyword(s):  
Solid Solution ◽  
Flexural Strength ◽  
Room Temperature ◽  
Composite Powder ◽  
Cost Effective ◽  
Combustion Method ◽  
Sintering Process ◽  
High Temperature Synthesis ◽  
Result Show

SiC whisker reinforced (Mo,W)Si2 composite powder has been successfully synthesized by a novel process, named as chemical oven self-propagating high temperature synthesis (COSHS). The mixtures of Si and Ti powders were ignited as chemical oven. XRD result shows that the combustion product is mainly composed of (Mo,W)Si2 solid solution and SiC phases. SEM photo and EDS result show that SiC whisker is formed during this process. The as-prepared SiCW/(Mo,W)Si2 composite powder has been pressureless sintered. The microstructure and mechanical properties of the composite were investigated. Relative densities of the monolithic material and composite are 91.2% and 92.2%, respectively. The composite containing SiC whisker and (Mo,W)Si2 solid solution has higher Vickers hardness than monolithic MoSi2. Especially the room-temperature flexural strength of the composite is higher than that of monolithic MoSi2, from 135.5MPa for MoSi2 to 235.6MPa for composites with 10 vol.% WSi2 and 15 vol.% SiC, increased by 73.9%. The morphology of fractured surface of composite reveals the mechanism to improve flexural strength of MoSi2. The results of this work show that in situ SiCW/(Mo,W)Si2 composite powder prepared by COSHS technique could be successfully sintered via pressureless sintering process and significant improvement of room temperature flexural strength could be achieved. It could be a cost-effective process for industry in future applications.

Microstructure and microtexture of a Nb-16%Si (DS) Alloy

1995 ◽  
Vol 53 ◽  
pp. 122-123
Author(s):  
J. A. Sutliff ◽  
B. P. Bewlay
Keyword(s):  
High Temperature ◽  
Directional Solidification ◽  
Room Temperature ◽  
Microstructural Characterization ◽  
Crystallographic Analysis ◽  
Directionally Solidified ◽  
Heat Treated ◽  
Other Orientation

In-situ composite Nb-Si alloys have been studied by several investigators as potential high temperature structural materials. The two major processing routes used to fabricate these composites are directional solidification and extrusion of arc-cast solidified ingots. In both cases a stable microstructure of primary Nb dendrites in a eutectoid of Nb and Nb5Si3 phases is developed after heat treatment. The Nb5Si3 phase is stable at room temperature and forms as a decomposition product of the high temperature Nb3Si phase. The anisotropic microstructures developed by both directional solidification and extrusion require evaluation of the texture to fully interpret the fracture and other orientation dependent mechanical behavior of these composites.In this paper we report on the microstructural characterization of a directionally solidified (DS) and heat treated Nb-16 at.%Si alloy. The microtexture of each of the phases (Nb, Nb5Si3) was determined using the Electron BackScattering Pattern (EBSP) technique for electron diffraction in the scanning electron microscope. A system employing automatic diffraction pattern recognition, crystallographic analysis, and sample or beam scanning was used to acquire the microtexture data.

IN-SITU Analysis Of The Microstructure of Thermally Treated Thin Copper Films

1993 ◽  
Vol 309 ◽  
Author(s):  
J. Nucci ◽  
H. Neves ◽  
Y. Shacham ◽  
E. Eisenbraun ◽  
B. Zheng ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Thermal Evolution ◽  
Electron Beam Evaporation ◽  
Copper Films ◽  
Tem Analysis ◽  
Heat Treated ◽  
Baseline Information

AbstractCopper thin films were deposited by sputtering, electron beam evaporation, and electroless plating onto nitride membranes for TEM analysis. The samples were heat treated in-situ from room temperature to 600 °C for structural and chemical analysis. The as-deposited and heat treated microstructures were investigated. Orientation changes with heat treatment and reactions among the sample layers were analyzed by electron diffraction. This work provides baseline information for a study of the thermal evolution of copper lines.

scholarly journals Nanoscale stacking fault–assisted room temperature plasticity in flash-sintered TiO2

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw5519 ◽  
Author(s):  
Jin Li ◽  
Jaehun Cho ◽  
Jie Ding ◽  
Harry Charalambous ◽  
Sichuang Xue ◽  
...  
Keyword(s):  
Room Temperature ◽  
Oxygen Vacancies ◽  
Crack Formation ◽  
High Stress ◽  
Ceramic Materials ◽  
Sintering Process ◽  
Flash Sintering ◽  
Structural Applications ◽  
Deformation Behaviors

Ceramic materials have been widely used for structural applications. However, most ceramics have rather limited plasticity at low temperatures and fracture well before the onset of plastic yielding. The brittle nature of ceramics arises from the lack of dislocation activity and the need for high stress to nucleate dislocations. Here, we have investigated the deformability of TiO2 prepared by a flash-sintering technique. Our in situ studies show that the flash-sintered TiO2 can be compressed to ~10% strain under room temperature without noticeable crack formation. The room temperature plasticity in flash-sintered TiO2 is attributed to the formation of nanoscale stacking faults and nanotwins, which may be assisted by the high-density preexisting defects and oxygen vacancies introduced by the flash-sintering process. Distinct deformation behaviors have been observed in flash-sintered TiO2 deformed at different testing temperatures, ranging from room temperature to 600°C. Potential mechanisms that may render ductile ceramic materials are discussed.

In Situ Synthesis of TiC-TiB2 Composites via High Energy Ball Milling and Pressureless Sintering

2013 ◽  
Vol 401-403 ◽  
pp. 635-638
Author(s):  
Ping Luo ◽  
Shi Jie Dong ◽  
Zhi Xiong Xie ◽  
Wei Yang ◽  
An Zhuo Yangli
Keyword(s):  
Ball Milling ◽  
Milled Powder ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Sintering Process ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Energy Ball

TiC-TiB2 composite ceramics were successfully fabricated via planetary ball milling of 72 mass% Ti and 28 mass % B4C powders, followed by low temperature sintering process at 1200°C. The microstructure of the ball-milled powder mixtures and composite ceramics were characterized by Differential thermal analysis equipment (DTA), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results showed that the ball-milled powder mixtures (Ti and B4C powders) were completely transformed to TiC-TiB2 composite ceramics as the powders were milled for 60 h and sintered at 1200°C for 1 h. The formation mechanism of the TiC-TiB2 composite was discussed. The high energy ball milling and necessary sintering for the powder mixtures plays an important role in the formation of the composites.

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