Mechanical Behaviour of Ultrafine Grained Cu and Cu-(2.5 and 5) Vol.%Al2O3 Composites Produced by Powder Compact Forging

2011 ◽  
Vol 275 ◽  
pp. 170-173
Author(s):  
Aamir Mukhtar ◽  
De Liang Zhang
Keyword(s):  
Composite Powder ◽  
Powder Compact ◽  
High Energy ◽  
High Yield ◽  
High Yield Strength ◽  
High Fracture ◽  
Composite Powders ◽  
Al2o3 Composite ◽  
Ultrafine Grained ◽  
Powder Compacts

Nanostructured Cu-(2.5 and 5)vol.%Al2O3 composite powders were produced from a mixture of Cu powder and Al2O3 nanopowder using high energy mechanical milling, and then compacted by hot pressing. The Cu and Cu-Al2O3 composite powder compacts were then forged into disks at temperatures in the range of 500-800°C to consolidate the Cu and Cu-Al2O3 composite powders. Tensile testing of the specimens cut from the forged disks showed that the Cu forged disk had a good ductility (plastic strain to fracture: ~15%) and high yield strength of 320 MPa, and the Cu-(2.5 and 5)vol.%Al2O3 composite forged disks had a high fracture strength in range of 530-600 MPa, but low ductility.

Microstructure and Mechanical Behaviour of Ultrafine Grained Al-4wt%Cu-(2.5-10) Vol.% SiC Metal Matrix Composites Produced by Powder Compact Forging

2011 ◽  
Vol 275 ◽  
pp. 208-213
Author(s):  
A. Gazawi ◽  
De Liang Zhang ◽  
K.L. Pickering ◽  
Aamir Mukhtar
Keyword(s):  
Metal Matrix ◽  
Powder Compact ◽  
Volume Fraction ◽  
High Energy ◽  
Matrix Composites ◽  
Plastic Yielding ◽  
Composite Powders ◽  
Ultrafine Grained ◽  
Powder Compacts ◽  
Small Plastic Strain

Ultrafine grained Al-4wt%Cu-(2.5-10) vol.% SiC metal matrix composite powders were produced from a mixture of Al, Cu and SiC powders using high energy mechanical milling (HEMM). The composite powders produced were first hot pressed at 300°C with a pressure of 240 MPa to produce cylindrical powder compacts with a relative density in the range of 80-94% which decreased with increasing the SiC volume fraction. Powder compact forging was utilized to consolidate the powder compacts into nearly fully dense forged disks. With increasing the volume fraction of SiC from 2.5% to 10%, the average microhardness of the forged disks increased from 73HV to 162HV. The fracture strength of the forged disks increased from 225 to 412 MPa with increasing the volume fraction of SiC particles from 2.5 to 10%. The Al-4wt%Cu-2.5vol.%SiC forged disk did not show any macroscopic plastic yielding, while the Al-4wt%Cu-(7.5 and 10)vol.% SiC forged disk showed macroscopic plastic yielding with a small plastic strain to fracture (~1%).

Synthesis of high-strength W–Ta ultrafine-grain composites

2008 ◽  
Vol 23 (1) ◽  
pp. 133-139 ◽  
Author(s):  
R.T. Ott ◽  
X.Y. Yang ◽  
D.E. Guyer ◽  
S. Chauhan ◽  
D.J. Sordelet
Keyword(s):  
High Strength ◽  
High Energy ◽  
High Temperature Phase ◽  
High Yield ◽  
Ultrafine Grain ◽  
Temperature Phase ◽  
Composite Powders ◽  
Ultrafine Grained ◽  
Submicron Scale ◽  
The Individual

Bulk samples of an ultrafine-grained tungsten–tantalum composite alloy have been synthesized by consolidating mechanically milled composite powders. The grain growth during densification is limited due to the submicron-scale layering of the individual metals in the composite particles and the relatively low sintering temperature (1300 °C). The ultrafine microstructure of the high-density (∼99% theoretical density) samples leads to a high yield stress of ∼3 GPa under quasi-static uniaxial compression. A tendency for Ta-rich solid-solution formation during densification was observed, and the high-temperature phase equilibria in the composite powders were examined further using high-energy x-ray diffraction at temperatures up to 1300 °C.

MICROSTRUCTURES AND MECHANICAL PROPERTIES OF ULTRAFINE GRAINED Ti-47Al-2Cr (at %) ALLOY PRODUCED USING POWDER COMPACT FORGING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1739-1744
Author(s):  
VIJAY N. NADAKUDURU ◽  
DELIANG ZHANG ◽  
PENG CAO ◽  
BRIAN GABBITTAS
Keyword(s):  
Mechanical Properties ◽  
Powder Compact ◽  
High Energy ◽  
Alloy Sample ◽  
Bulk Alloy ◽  
Porosity Level ◽  
Fine Grain ◽  
Ultrafine Grained ◽  
Powder Compacts ◽  
Innovative Techniques

Development of innovative techniques to produce gamma TiAl based alloys, with good mechanical properties, while still maintaining ultra fine grain size can be rewarding, but also is a great challenge. In the present study study a Ti -47 Al -2 Cr ( at %) alloy has been synthesized by directly forging green powder compacts of a Ti / Al / Cr composite powder produced by high energy mechanical milling of a mixture of elemental Ti , Al , Cr powders. It has been found that the density of the bulk consolidated alloy sample after forging decreases from 95% of the theoretical density in the central region to 84% in the periphery region. The microstructure of the bulk alloy consisted of several Ti rich regions, which was expected to be mainly due to initial powder condition. The room temperature tensile strength of the samples produced from this process was found to be in the range of 115 – 130 MPa. The roles of canning and green powder compact density in determining the forged sample porosity level and distribution are discussed.

scholarly journals Pulse Plasma Sintering of NiAl-Al2O3 Composite Powder Produced by Mechanical Alloying with Contribution of Nanometric Al2O3 Powder

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 407
Author(s):  
Katarzyna Konopka ◽  
Justyna Zygmuntowicz ◽  
Marek Krasnowski ◽  
Konrad Cymerman ◽  
Marcin Wachowski ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Composite Powder ◽  
Pulse Plasma ◽  
Alumina Powder ◽  
Composite Powders ◽  
Plasma Sintering ◽  
Al2o3 Composite ◽  
Ultrafine Grained ◽  
Pulse Plasma Sintering ◽  
Nial Matrix

NiAl-Al2O3 composites, fabricated from the prepared composite powders by mechanical alloying and then consolidated by pulse plasma sintering, were presented. The use of nanometric alumina powder for reinforcement of a synthetized intermetallic matrix was the innovative concept of this work. Moreover, this is the first reported attempt to use the Pulse Plasma Sintering (PPS) method to consolidate composite powder with the contribution of nanometric alumina powder. The composite powders consisting of the intermetallic phase NiAl and Al2O3 were prepared by mechanical alloying from powder mixtures containing Ni-50at.%Al with the contribution of 10 wt.% or 20 wt.% nanometric aluminum oxide. A nanocrystalline NiAl matrix was formed, with uniformly distributed Al2O3 inclusions as reinforcement. The PPS method successfully consolidated NiAl-Al2O3 composite powders with limited grain growth in the NiAl matrix. The appropriate sintering temperature for composite powder was selected based on analysis of the grain growth and hardness of Al2O3 subjected to PPS consolidation at various temperatures. As a result of these tests, sintering of the NiAl-Al2O3 powders was carried out at temperatures of 1200 °C, 1300 °C, and 1400 °C. The microstructure and properties of the initial powders, composite powders, and consolidated bulk composite materials were characterized by SEM, EDS, XRD, density, and hardness measurements. The hardness of the ultrafine-grained NiAl-Al2O3 composites obtained via PPS depends on the Al2O3 content in the composite, as well as the sintering temperature applied. The highest values of the hardness of the composites were obtained after sintering at the lowest temperature (1200 °C), reaching 7.2 ± 0.29 GPa and 8.4 ± 0.07 GPa for 10 wt.% Al2O3 and 20 wt.% Al2O3, respectively, and exceeding the hardness values reported in the literature. From a technological point of view, the possibility to use sintering temperatures as low as 1200 °C is crucial for the production of fully dense, ultrafine-grained composites with high hardness.

scholarly journals Influence of Oxide Additions in Cu-Co-Fe Composite Powders Obtained by Mechanical Alloying

2014 ◽  
Vol 783-786 ◽  
pp. 1548-1553
Author(s):  
Núria Llorca-Isern ◽  
Cristina Artieda-Guzman ◽  
Jose Alberto Vique ◽  
Antoni Roca
Keyword(s):  
Mechanical Alloying ◽  
Crystallite Size ◽  
Composite Powder ◽  
Milling Time ◽  
High Energy ◽  
Milling Process ◽  
Composite Powders ◽  
Ceramic Particles ◽  
Pure Cu ◽  
Ceramic Reinforcement

Nanocrystalline composite powders were prepared by mechanical alloying of pure Cu, Fe and Co as metallic major part and Al2O3 or Fe2O3 or SiO2 as ceramic reinforcement in a high-energy ball mill. Alloys of the copper-iron-cobalt system are promising for the development of new materials and applications. Cu-Fe-Co is used in different applications depending on the properties required. These can be related for example to toughness when used as rock cutting tool, to magnetic and electric properties for microelectronics or to chemical behaviour when used as catalysts in bioalcohol production industry. The objective of the present study is to contribute to understanding how and to which amount the ceramic reinforcement affects the properties for which this Cu-Fe-Co system is used as well as to envisage other less frequently uses for the composite powders. Structural and magnetic transformations occurring in the material during milling were studied with the use of X-ray diffraction, scanning quantum induction device (SQUID) and magnetic force microscopy (MFM). In mechanical alloying the transformations depend upon milling time. The results showed that milling the elemental powders of Cu-Fe-Co in the mass proportion of 50:25:25 respectively for times up to 10h leads to the progressive dissolution of Fe and Co atoms into FCC Cu and the final product of the MA process was the nanocrystalline Cu containing Fe and Co with a mean crystallite size (from coherent crystal size determination by diffraction) of 20 nm aprox. When ceramic particles are milled together with the metals (at proportions of the oxides between 1-10%) this mechanism is retarded. On the other hand, the lowest mean crystallite size is reached without ceramic particles in the milling process. However the composite powder produced in all the cases stabilized similar lowest crystallite size between 45-50 nm. Mechanically alloyed metallic-ceramic composite powder showed lower saturation magnetization than the metallic system but enhanced coercive field (significantly for hematite reinforcement). All the studied systems are intermediate ferromagnetics (Hc≈104 A/m). Milling time significantly affects the structure, composition and properties for both metallic and composite systems.

Production of Al–20 wt.% Al2O3 composite powder using high energy milling

2009 ◽  
Vol 192 (3) ◽  
pp. 346-351 ◽  
Author(s):  
S.S. Razavi Tousi ◽  
R. Yazdani Rad ◽  
E. Salahi ◽  
I. Mobasherpour ◽  
M. Razavi
Keyword(s):  
Composite Powder ◽  
High Energy ◽  
High Energy Milling ◽  
Al2o3 Composite

Comparison of Blended Elemental (BE) and Mechanical Alloyed (MA) Powder Compact Forging into Ti-6Al-4V Rocker Arms

2012 ◽  
Vol 520 ◽  
pp. 82-88 ◽  
Author(s):  
Ming Tu Jia ◽  
De Liang Zhang ◽  
Brian Gabbitas
Keyword(s):  
Master Alloy ◽  
Internal Combustion Engines ◽  
Powder Compact ◽  
High Energy ◽  
Combustion Engines ◽  
Alloyed Powder ◽  
Blended Elemental ◽  
Blended Powder ◽  
Forged Parts ◽  
Powder Compacts

Ti-6Al-4V rocker arms for internal combustion engines were produced by forging of compacts of blended powder consisting of elemental hydride-dehydride (HDH) titanium powder and Al60V40 (wt%) master alloy powder or mechanical alloyed (MA) powder synthesized by high energy mechanical milling of a mixture of HDH titanium and Al60V40 master alloy powders. The powder compacts were made by warm compaction, and their relative density was 90%. The mechanical properties and microstructures of as-forged parts made using blended powder were improved significantly with increasing holding time at forging temperature, and close to those of as-forged parts produced by powder compact forging of HDH Ti-6Al-4V pre-alloyed powder. However, the as-forged part produced by powder compact forging of MA powder was brittle, and fractured prematurely during tensile testing.

scholarly journals Densification of Particulate Ceramic Composites: The Role of Heterogeneities

1989 ◽  
Vol 155 ◽  
Author(s):  
Lutgard C. De Jonghe ◽  
Mohamed N. Rahaman
Keyword(s):  
Composite Powder ◽  
Powder Compact ◽  
Ceramic Powder ◽  
Ceramic Composites ◽  
Negative Effects ◽  
Alternative Processing ◽  
Inclusion Phase ◽  
Die Compaction ◽  
Powder Compacts

ABSTRACTInert p articulate inclusions in ceramic powder compacts can obstruct densification behavior significantly. The factors that are the causes of this decrease in the sinterability are reviewed. It is concluded that the origin of the sintering difficulty resides in defects that processes such as die compaction introduce during the initial forming of the composite powder compact. Alternative processing methods are suggested that should minimize the negative effects of the dispersed inclusion phase on densification.

Studies on Microstructure of Cu-SiC Compounds by Mechanical Alloying

2015 ◽  
Vol 1089 ◽  
pp. 76-79
Author(s):  
Liang Chen ◽  
Zhan Wen He
Keyword(s):  
Particle Size ◽  
Lattice Constant ◽  
Ball Mill ◽  
Composite Powder ◽  
High Energy ◽  
Powder Particle Size ◽  
Micro Structure ◽  
Composite Powders ◽  
High Energy Ball Mill ◽  
Energy Ball

Cu - SiC composite powders were discussed in this paper the microstructure after ball mill, through to the ball mill after Cu-SiC composite powder particle size and lattice constant analysis, confirmed the high-energy ball mill to Cu-SiC micro structure of the binary alloy. The experimental results show that the ball mill after 20 h, Cu particle size has a larger extent reduce after high-energy ball mill and SiC lattice constant increase.

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