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Scripta MATERIALIA PERGAMON Scripta Materialia 45(2001)541-546 www.elsevier.com/locate/scriptamat Aging behavior and tensile properties of 6061A1-0.3 um Al2O3p particle composites produced by reciprocating extrusion Hsu-Shen Chu,Kuo-Shung Liu,and Jien-Wei Yeh* Department of Materials Science and Engineering.National Tsing Hua University,Hsinchu 30043,Taiwan,ROC Received 10 March 2000;accepted 5 January 2001 Abstract 6061A1-0.3 um Al2O3p composites are fully densified from powder compact by reciprocating extrusion. Al2O3 particles are dispersed uniformly in the matrix.The composites exhibit excellent ductility caused by the mechanical kneading of reciprocating extrusion.©2O0 I Acta Materialia Inc.Published by Elsevier Science Ltd.All rights reserved. Keywords:Reciprocating extrusion;Composites;Aging response;Work-hardening Introduction Particle reinforced Al composites have become attractive materials for use in aero- space structures,automobile engineering and semiconductor packaging.These com- posites deserve consideration due to their advanced properties,such as low density, high specific stiffness,strength,and wear resistance [1-3]. The composites can be fabricated by casting processes or powder metallurgi- cal methods.Casting processes such as squeeze casting,compocasting and the vortex method are cost effective.However,they involve serious problems of tensile ductility following from segregation,pores and relatively large particle size.The powder metal- lurgical method introduces particle clustering,interparticle oxide layers and con- tamination in the as-pressed state.These defects cause damage cracks and limit the applications of powder metallurgical products [4,5].Improving the fabrication pro- cessing to make fine particles homogeneously disperse and to remove harmful defects in the composites,is therefore important. Corresponding author. E-mail address:jwyeh@mse.nthu.edu.tw(J.-W.Yeh). 1359-6462/01/S-see front matter 2001 Acta Materialia Inc.Published by Elsevier Science Ltd.All rights reserved. PIL:S1359-6462(01)01055-7 ! " # $ ! % # & ' () !"# * + , - & . / 0 1 + 2 3 4 ! % $ % * , " , , ' 1 3 # 1 0 # / # . 5# # / 67 0 / " 8 9 # 5 / # / # 9 0 / # 0 1 / 6:#-7 2 1 . # ! + :- ;< -:-: /// = = ) " 4 > ?/ @ / ;& ' (< -A :==B + 2 3 4 ! % 322> ! - A : ; < - - C