scholarly journals Characterization of mechanically milled and spark plasma sintered Al2124-CNT nanocomposites

2015 ◽  
Vol 47 (2) ◽  
pp. 119-129 ◽  
Author(s):  
N. Saheb
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
Lattice Strain ◽  
Sintering Temperature ◽  
Aluminum Matrix ◽  
Sintering Time ◽  
The Matrix ◽  
Spark Plasma ◽  
Aluminum Phase

In the present work, ball milling and spark plasma sintering were used to develop Al2124-CNT nanocomposites. The effect of milling time on the grain size and lattice strain of the ball milled Al2124 alloy powder and the effect of sintering time and temperature on the grain size of the matrix in spark plasma sintered Al2124 alloy and CNT-reinforced Al2124 nanocomposites were investigated. The density and hardness of the developed materials were evaluated as functions of the sintering parameters. It was found that ball milling not only reduced the particle size of the Al2124 powder but also decreased the grain size of the ?-aluminum phase to 50 nm and increased its lattice strain. A milling time of 6 hours was found to be the optimum time to reach a nanostructured ?-aluminum matrix. The grain size of the ?-aluminum phase in the sintered samples increased with increasing sintering temperature and time to reach maximum values at a sintering temperature of 500?C and a sintering time of 20 minutes. Although sintering led to grain growth, the grain size of the ?-aluminium matrix remained in the nanometer range and did not exceed 150 nm. The relative density and hardness of the sintered samples increased with increasing sintering temperature and time to reach maximum values at a sintering temperature of 500?C and a sintering time of 20 minutes.

Production of Dispersion-Strengthened Cu-TiB2 Alloys by Ball-Milling and Spark-Plasma Sintering

2007 ◽  
Vol 534-536 ◽  
pp. 1489-1492 ◽  
Author(s):  
Dae Hwan Kwon ◽  
Jong Won Kum ◽  
Thuy Dang Nguyen ◽  
Dina V. Dudina ◽  
Pyuck Pa Choi ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Ball Mill ◽  
Milling Time ◽  
Rotation Speed ◽  
Sintering Temperature ◽  
Milled Powder ◽  
Plasma Sintering ◽  
Spark Plasma

Dispersion-strengthened copper with TiB2 was produced by ball-milling and spark plasma sintering (SPS).Ball-milling was performed at a rotation speed of 300rpm for 30 and 60min in Ar atmosphere by using a planetary ball mill (AGO-2). Spark-plasma sintering was carried out at 650°C for 5min under vacuum after mechanical alloying. The hardness of the specimens sintered using powder ball milled for 60min at 300rpm increased from 16.0 to 61.8 HRB than that of specimen using powder mixed with a turbular mixer, while the electrical conductivity varied from 93.40% to 83.34%IACS. In the case of milled powder, hardness increased as milling time increased, while the electrical conductivity decreased. On the other hand, hardness decreased with increasing sintering temperature, but the electrical conductiviey increased slightly

Spark Plasma Sintering of High-Energy Ball-Milled ZrB2 and HfB2 Powders with 20vol% SiC

2018 ◽  
Vol 941 ◽  
pp. 1990-1995
Author(s):  
Naidu V. Seetala ◽  
Cyerra L. Prevo ◽  
Lawrence E. Matson ◽  
Thomas S. Key ◽  
Ilseok I. Park
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Micro Hardness ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Ball Milling Time

ZrB2 and HfB2 with incorporation of SiC are being considered as structural materials for elevated temperature applications. We used high energy ball milling of micron-size powders to increase lattice distortion enhanced inter-diffusion to get uniform distribution of SiC and reduce grain growth during Spark Plasma Sintering (SPS). High-energy planetary ball milling was performed on ZrB2 or HfB2 with 20vol% SiC powders for 24 and 48 hrs. The particle size distribution and crystal micro-strain were examined using Dynamic Light Scattering Technique and x-ray diffraction (XRD), respectively. XRD spectra were analyzed using Williamson-Hall plots to estimate the crystal micro-strain. The particle size decreased, and the crystal micro-strain increased with the increasing ball milling time. The SPS consolidation was performed at 32 MPa and 2,000°C. The SEM observation showed a tremendous decrease in SiC segregation and a reduction in grain size due to high energy ball milling of the precursor powders. Flexural strength of the SPS consolidated composites were studied using Four-Point Bend Beam test, and the micro-hardness was measured using Vickers micro-indenter with 1,000 gf load. Good correlation is observed in SPS consolidated ZrB2+SiC with increased micro-strain as the ball milling time increased: grain size decreased (from 9.7 to 3.2 μm), flexural strength (from 54 to 426 MPa) and micro-hardness (from 1528 to 1952 VHN) increased. The correlation is less evident in HfB2+SiC composites, especially in micro-hardness which showed a decrease with increasing ball milling time.

Research on Two Sintered Techniques of Nanometer WC-Co Powder

2007 ◽  
Vol 534-536 ◽  
pp. 593-596 ◽  
Author(s):  
Lan Sun ◽  
Cheng Chang Jia ◽  
Hua Tang
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Spark Plasma Sintering ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Grain Sizes ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Hot Pressing Sintering

This paper concerned with SPS (spark plasma sintering), hot pressing of sinter nanometer WC-Co powder and discussed the density, hardness, microstructures and grain sizes of the alloys sintered by different styles. The results showed that SPS could lower the sintering temperature, increased the density and circumscribed the growth of grain size of WC. Hot pressing sintering could produce high density alloys and play well on the grain growth, but its sintering temperature and sintering time were larger than SPS. Besides, the hardness of the sintered cemented alloys that was dependent on the grain size and densification could also be improved by SPS and hot pressing.

scholarly journals Microstructure and Mechanical Properties of Nanocrystalline Al-Zn-Mg-Cu Alloy Prepared by Mechanical Alloying and Spark Plasma Sintering

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1255 ◽  
Author(s):  
Cheng ◽  
Cai ◽  
Zhao ◽  
Yang ◽  
Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Milling Time ◽  
Milled Powder ◽  
Bulk Alloy ◽  
Engineering Strain ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Ball Milling Time

In this study, Al, Zn, Mg and Cu elemental metal powders were chosen as the raw powders. The nanocrystalline Al-7Zn-2.5Mg-2.5Cu bulk alloy was prepared by mechanical alloying and spark plasma sintering. The effect of milling time on the morphology and crystal structure was investigated, as well as the microstructure and mechanical properties of the sintered samples. The results show that Zn, Mg and Cu alloy elements gradually dissolved in α-Al with the extension of ball milling time. The morphology of the ball-milled Al powder exhibited flaking, crushing and welding. When the ball milling time was 30 h, the powder particle size was 2–5 μm. The α-Al grain size was 23.2 nm. The lattice distortion was 0.156% causing by the solid solution of the metal atoms. The grain size of ball-milled powder grew during the spark plasma sintering process. The grain size of α-Al increased from 23.2 nm in the powder to 53.5 nm in the sintered sample during the sintering process after 30 h of ball milling. At the same time, the bulk alloy precipitated micron-sized Al2Cu and nano-sized MgZn2 in the α-Al crystal. With the extension of ball milling time, the compression strength, yield strength and Vickers hardness of spark plasma sintering (SPS) samples increased, while the engineering strain decreased. The compression strength, engineering strain and Vickers hardness of sintered samples prepared by 30 h milled powder were ~908 MPa, ~8.1% and ~235 HV, respectively. The high strength of the nanocrystalline Al-7Zn-2.5Mg-2.5Cu bulk alloy was attributed to fine-grained strengthening, dislocation strengthening and Orowan strengthening due to the precipitated second phase particles.

Development of Ni/h-BN Self-Lubricating Composite Powder by High-Energy Ball Milling

2016 ◽  
Vol 869 ◽  
pp. 277-282
Author(s):  
Moisés Luiz Parucker ◽  
César Edil da Costa ◽  
Viviane Lilian Soethe
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Solid Lubricants ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Second Phase ◽  
Average Particle ◽  
Composite Powders ◽  
The Matrix ◽  
Energy Ball

Solid lubricants have had good acceptance when used in problem areas where the conventional lubricants cannot be applied: under extreme temperatures, high charges and in chemically reactive environments. In case of materials manufactured by powder metallurgy, particles of solid lubricants powders can be easily incorporated to the matrix volume at the mixing stage. In operation, this kind of material provides a thin layer of lubricant that prevents direct contact between the surfaces. The present study aimed at incorporating particles of second phase lubricant (h-BN) into a matrix of nickel by high-energy ball milling in order to obtain a self-lubricating composite with homogeneous phase distribution of lubricant in the matrix. Mixtures with 10 vol.% of h-BN varying the milling time of 5, 10, 15 and 20 hours and their relationship ball/powder of 20:1 were performed. The effect of milling time on the morphology and microstructure of the powders was studied by X-ray diffraction, SEM and EDS. The composite powders showed reduction in average particle size with increasing milling time and the milling higher than 5 hours resulted in equiaxial particles and the formation of nickel boride.

Carbon Nanotubes Reinforced Aluminum Matrix Composites by High-Energy Ball Milling

2010 ◽  
Vol 150-151 ◽  
pp. 1163-1166 ◽  
Author(s):  
Xiao Fei Wang ◽  
Xiao Lan Cai
Keyword(s):  
Mechanical Properties ◽  
Ball Milling ◽  
Milling Time ◽  
Aluminum Matrix ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Energy Ball ◽  
Rotary Speed

CNT-reinforced aluminum matrix composites was produced by high-energy ball milling, the effect of rotary speed and milling time on the particle size distribution,the density and hardness of CNT-aluminum matrix composites were studied,it was observed that the rotary speed and milling time have an important effect on the mechanical properties of the CNT-aluminum matrix composites.

The Effect of Reinforcement Phase on the Microstructure of Al-SiC Nanocomposite Powder Prepared via Mechanical Alloying

2009 ◽  
Vol 83-86 ◽  
pp. 764-770
Author(s):  
Taha Rostamzadeh ◽  
H. Shahverdi ◽  
R. Sarraf-Mamoory ◽  
A. Shanaghi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Metal Matrix ◽  
Milling Time ◽  
Lattice Strain ◽  
Volume Fraction ◽  
Aluminum Matrix ◽  
High Energy ◽  
Nanocomposite Powder ◽  
Nanocomposite Powders

Mechanical alloying is one of the most successful methods for the manufacturing of metal matrix nanocomposite powders. In this study, Al/SiC metal matrix composite (MMCp) powders with volume fractions of 5, 10, and 15 percent SiC were successfully obtained after milling the powder for a period of 25 hours at a ball to powder ratio of 15:1 using high energy planetary milling. The Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to investigate the lattice strain of the matrix phase and the microstructure of the nanocomposite powders after 1, 10, and 25 hours of milling time. Also, the morphology of the Al-5%SiC nanocomposite powder was investigated using transmission electron microscopy (TEM). The results show that with the increase of both milling time and the reinforcement phase volume fraction, the lattice strain increases and the average size of aluminum phase crystallites decreases. Eventually, after 25 hours of milling, the nanocomposite powders show a spherical-like morphology and SiC particles were distributed in an aluminum matrix with appropriate order.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Nanocrystalline Aluminum 5083 Alloy

2015 ◽  
Vol 782 ◽  
pp. 113-118
Author(s):  
Ying Mei Teng ◽  
Zhao Hui Zhang ◽  
Zi Zhou Yuan
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Compressive Strength ◽  
Sintering Temperature ◽  
Initial Pressure ◽  
Fine Grain ◽  
Microstructure And Mechanical Properties ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Bulk Nanocrystalline

The bulk nanocrystalline (NC) aluminum (Al) 5083 was synthesized by spark plasma sintering (SPS) technique with low initial pressure of 1 MPa, high holding pressure of 300 MPa and holding time of 4 min at different sintering temperatures, using surface passivated nanopowders. The effect of sintering temperature on microstructure and mechanical properties of the bulk NC Al 5083 were investigated. Results indicate that the density, grain size, the hardness and the compressive strength of the bulk NC Al 5083 increase with an increase in sintering temperature. The mechanical properties of the material are greatly improved due to the fine grain size. The bulk NC Al 5083 sintered at 723 K has the highest micro-hardness of 2.37 GPa and the best compressive strength of 845 MPa.

Effect of Milling Time on the Properties of Nanocrystalline CuCr50 Alloys

2011 ◽  
Vol 299-300 ◽  
pp. 824-827
Author(s):  
Kun Yu Shi ◽  
Tao Shen ◽  
Li Hong Xue ◽  
Chun Hao Chen ◽  
You Wei Yan
Keyword(s):  
Electrical Conductivity ◽  
Crystallite Size ◽  
Milling Time ◽  
Micro Hardness ◽  
Uniform Microstructure ◽  
High Relative Density ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Bulk Nanocrystalline

Nanocrystalline CuCr50 alloys were fabricated by means of mechanical alloying and spark plasma sintering. The influence of milling time on the as-milled powders and properties of sintered compacts were investigated. The results show that crystallite size of powders decreases gradually with increase of milling time, while the micro-strain increases firstly then decreases correspondingly. The crystallite size is 22 nm at milling 100h.The micro-hardness of the compacts improves greatly with the increase of milling time, reaching 363HV at 150h which is about 3 times as high as that of the industrial standard (120HV), while the electrical conductivity improves gradually decline. The bulk nanocrystalline CuCr50 alloys sintered at 900°C for 5min exhibit high relative density of 96% and uniform microstructure: nanoparticles Cr with size of about 120nm are uniformly dispersed in the matrix.

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