Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
TEM study of Al-SiC nanocomposite powders
Taha Rostamzadeh, 1,2 * and Hamid Reza Shahverdi 2
1 Department of Electronic Engineering, Faculty of Engineering, Islamic Azad University, Garmsar Branch, Garmsar, Iran
2 Department of Nano-Material Engineering, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran
Abstract-In this study Al-5%SiCp nanocomposite powders has been successfully synthesized by high-energy planetary milling of Al and SiC.
The nanocomposite powders microstructure have been investigated by transmission electron microscopy (TEM), scanning electron microscopy
(SEM), and X-ray diffraction (XRD) analyses. The results show that after 25 h of milling, nanocomposite powders composed of near-spherical
particles were obtained.
Incorporation of ceramic particulates into the metallic matrix
can be accomplished by several techniques, such as moltenmetal
routes or solid-state processing [1-3]. It should be noted
that Al-SiC composites are difficult to obtain by conventional
melting-based methods due to the poor wettability between
molten Al and the SiC. The mechanical alloying process
involves repeated welding and fracturing of a mixture of
powder particles to produce an extremely fine microstructure
of Al-SiC nanocomposite [4-6]. As the morphology of
nanocomposite powder has considerable effect on the
properties of mechanically milled powder, this study was
designed and undertaken to consider the microstructure of
nanocomposite powder.
In this work, Aluminum and SiC powders were mixed to
give a nominal composition of Al-5%SiC. The preparation of
the nanocomposite powders by mechanical milling of the
mixed powder was carried out using a high-energy planetary
ball mill in an argon atmosphere. A rotational speed of
300 rpm and a ball-to-powder weight ratio of 15:1 were
employed. To avoid agglomeration and the cold welding of
powder particles, stearic acid amounting to 1.5 wt% of the
total powder charge was used as a process control agent.
parallel appearance probably related to severe deformation
come by mechanical alloying process.
Figure 2. SEM morphologies of Al–5% SiC after 25h of MA
Figure 3. (a) Bright-field image (BFI) and (b) selected-area
diffraction pattern SADP) of Al-5%SiC milled powders for 25h
Figure 1. X-ray diffraction pattern of Al-5%SiC milled powders for
25h
Figure 1 shows the XRD patterns of the nanocomposite
powder. The final product consists of Al and SiC mixture and
there is no formation of any other phase such as Al 4 C 3 and Si.
Fig. 2 shows the SEM image of the agglomerated spherical
nanocomposite powder obtained after 25 h of MA.
Figs. 3 (a) and (b) show a bright-field image (BFI) and a
selected-area diffraction pattern (SADP), respectively, of the
nanocomposite powder obtained after 25 h of ball-milling. The
bright-field image indicates that there are some nearly
spherical nanoparticles, approximately 5–20 nm in diameter,
and some layered structures of greater size (Fig. 3 (a)). The
SADP shows a quite sharp ringspot pattern characteristic of
diffracting polycrystalline co mponents. EDS analysis proved
the existence of Al and SiC components. Fig. 4 shows BFI
image of powders in high magnification. There are some
nearly parallel lines in that. As the distance between this lines
are more than the space of crystallite p lanes, theses nearly
Figure 4. Bright-field image of nanocomposite powders in high
magnification
In summary, by using high energy ball milling of the
mixture of powders, SiC nanometer sized particle reinforced
Al–SiC composite powder can be obtained. The TEM analysis
and morphological study has revealed that the agglomerated
powders consist of many layers and that they contain
embedded spherical nanoparticles. In addition it seems that
MA process induces severe plastic deformation in the
composite.
*Corresponding author: shahverdi@modares.ac.ir
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2540 (2005)
[2] M. Sherif El-Eskandarany, Journal of Alloys and Compounds
279:263-271(1998)
[3] K.B. Lee, H.S Sim, J. Matter. Sci 36:3179 – 3188 (2001)
[4] C Suryanarayana, Progress in Materials Science 46:1-184 (2001)
[5] D.L. Zhang, Progress in Materials Science 49:537–560 (2004)
[6] S.M Zebarjad, S.A Sajjadi Materials and Design 27:684–688
(2006)
6th Nanoscience and Nanotechnology Conference, zmir, 2010 357