Preparation of Super-High Strength Bimodal Aluminum Based Nanocomposite Via Mechanical Alloying and Hot Extrusion

Document Type : Research Paper

Authors

Abstract

In this paper, bimodal Aluminum based nanocomposite prepared via mechanical alloying and hot extrusion. Mechanical alloying was used to synthesize Al2024 nanostructured powder in attrition mill under argon atmosphere up to 50 h. After mixing nanostructured aluminum and unmilled aluminum powders in low energy ball mill, the resulting composite powders were shaped through hot Pressing. Finally, the hot pressed powders were hot extruded. The microstructure and fracture surface were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectrometry (EDS). In order to compare the mechanical properties of hot extruded samples, tensile, compression, and hardness tests were performed. Results showed that, with an increase in unmilled aluminum percentage, ductility of composite increased but strength and hardness decreased. The mechanisms for the simultaneously improved strength and ductility involves increased dislocation activity in the coarse-grained (i.e., unmilled powder) regions as a result of the constraint of plastic deformation in these coarse-grained regions.

Keywords


1- B. Ahn, and S.R. Nutt, “Strain Mapping
of Al–Mg Alloy with Multi-scale Grain
Structure using Digital Image Correlation
Method”, Experimental Mechanics, Vol.
50, pp 117–123, 2010.
2- Z. Lee, D.B. Witkin, V. Radmilovic,
E.J. Lavernia, and S.R. Nutt, “Bimodal
microstructure and deformation of
cryomilled bulk nanocrystalline Al–7.5Mg
alloy”; Materials Science and Engineering
A, Vols. 410–411, pp 462–467, 2005.
3- D. Witkin, B.Q. Han, and E.J. Lavernia,
“Mechanical Behavior of UltrafineGrained Cryomilled Al 5083 at Elevated
Temperature”; Journal of Materials
Engineering and Performance, Vol. 14, pp
519-527, 2005.
4- D. Witkin, B.Q. Han, and E.J. Lavernia,
“Room-Temperature Mechanical Behavior
of Cryomilled Al Alloys”; Metallurgical
and Materials Transactions A, Vol. 37, pp
185-194, 2006.
5- A. Yamashita, D. Yamaguchi, Z. Horita,
and T.G. Langdon, "Influence of pressing
temperature on microstructural
development in equal channel angular
pressing"; Materials Science and
Engineering A, Vol. 287, pp 100–106,
2000.
6- J.H. Ahn, Y.J. Kim, and H. Chung, “AlAlN Tri-modal Composites prepared by
Mechanical Alloying”, Rev. Adv. Mater.
Sci, Vol. 18, pp 329-334, 2008.
7- D. Witkin, Z. Lee, R. Rodriguez, S.
Nutt, and E. Lavernia, “Al–Mg alloy
engineered with bimodal grain size for
high strength and increased ductility”,
Scripta Materialia, Vol. 49, pp 297–302,
2003.
8- C. Hofmeister, B. Yao, Y.H. Sohn, T.
Delahanty, M. Bergh, and K. Cho,
“Composition and structure of nitrogencontaining dispersoids in trimodal
aluminum metal–matrix composites”,
Journal of Materials Science, Vol. 45, pp
4871–4876, 2010.
9- B.Q. Han, J. Ye, F. Tang, J. Schoenung,
and E.J Lavernia, “Processing and
behavior of nanostructured metallic alloys
and composites by Cryomilling”, Journal
of Materials Science, Vol. 42, pp 1660–
1672, 2007.
10- R.W. Hayes, D. Witkin, F. Zhou, and
E.J. Lavernia, “Deformation and activation
volumes of cryomilled ultrafine-grained
aluminum”, Acta Materialia, Vol. 52, pp
4259–4271, 2004.
11- S.S. Razavi Tousi, R. Yazdani Rad, E.
Salahi, I. Mobasherpour, and M. Razavi,
“Production of Al–20 wt.% Al2O3
composite powder using high energy
milling”, Powder Technology, Vol. 192,
pp 346–351, 2009.
12 -ر. اسدیفرد، ن. پروین، ج. آقازاده و پ. صفارزاده،
"بررسی تأثیر فرایند آلیاژسازی مکانیکی بر مورفولوژی و
اندازه دانه پودرهای کامپوزیتی SiCp-Al6061"؛
هشتمین کنگره سالانه انجمن مهندسین متالورژی ایران؛
دانشکده مهندسی مواد دانشگاه صنعتی اصفهان؛ مهرماه
.1383
13- J.B. Fogagnolo, F. Velasco, M.H.
Robert, and J.M. Torralba, “Effect of
mechanical alloying on the morphology,
microstructure and properties of
aluminium matrix composite powders”,
Materials Science and Engineering A, Vol.
342, pp 131-143, 2003.
14 -ع. علیزاده، "ساخت و بررسی خواص مکانیکی و
سایشی نانوکامپوزیت B4C-Al ،"پایاننامه دکتری،
دانشکده فنی و مهندسی دانشگاه تربیت مدرس، 1390 .
15- N. Zhao, P. Nash, and X. Yang, “The
effect of mechanical alloying on SiC
distribution and the properties of 6061
aluminum composite”, Journal of
Materials Processing Technology, Vol.
170, pp586-592, 2005.
16- G.J. Fan, H. Choo, P.K. Liaw, and E.J.
Lavernia, “Plastic deformation and fracture
of ultrafine-grained Al–Mg alloys with a
bimodal grain size distribution”; Acta
Materialia, Vol. 54, pp 1759–1766, 2006.
17 -ن. نصیریان و خ. رنجبر، "بررسی خواص مکانیکی و
ریزساختاری کامپوزیت Brass/Al ساخته شده به روش
اتصال نوردی تجمعی" مجله مواد نوین، جلد 3 ،شماره 1،
 .1391 پاییز، 54 -45 صص
18- R.G. Vogt, Z. Zhang, T.D. Topping,
E.j. Lavernia, and J.M. Schoenung,
“Cryomilled aluminum alloy and boron
carbide nano-composite plate”, Journal of
Materials Processing Technology, Vol.
209, pp 5046–5053, 2009.