International Journal of Modern Physics B tt.Si_ u# I~I c * vr Vol. 22, Nos. 18 & 19 (2008) 2924-2932 V © World Scientific ' v J mifl www.worldscientific.com © World Scientific Publishing Company EFFECT OF MECHANICAL ALLOYING PROCESS PARAMETERS ON CHARACTERISTICS OF AI-B4CNANOCOMPOSITE-NANOCRYSTLLINE POWDER PARTICLES MEHRDAD KHAKBIZ School of Metallurgy and Materials Engineering, Center of Excellence for High Performance Materials, University of Tehran, P.O. Box 11365-4563, Tehran, Iran khakbiz @ ut. ac. ir FARSHAD AKHLAGHI School of Metallurgy and Materials Engineering , Center of Excellence for High Performance Materials, University of Tehran, P.O. Box 11365-4563, Tehran, Iran, Fakhlagh @ ut. ac. ir Received 20 June 2008 In the present work the effect of milling time (2-16h), milling speed (320 and 420rpm), as-received aluminum particle size (21 and 71 urn), B 4 C size (90, 700 and 1200nm) and its content (5% and 10%) on the characteristics of A1-B 4 C powder particles during milling was investigated by scanning electron microscopy (SEM) and laser particle size (LPS) analyzer. X-ray diffraction was used to investigate the crystal size and internal strains within the processed aluminum particles at different conditions. It was concluded that powder particles size increased after 4h milling but further milling (up to 16h) resulted in decreased powder particles size. By increasing milling speed from 320rpm to 420rpm, finer aluminum powder particle sizes were obtained in any specific milling time. XRD results confirmed that nanocrystalline structures with the size of 80nm for aluminum powder particles can be achieved in different milling conditions. SEM micrographs and EDX maps of Al- B 4 C mixtures confirmed that milling at optimum conditions breaks the reinforcement particle clusters and a homogenous distribution of B 4 C nanoparticles in A1-B 4 C powder mixture can be achieved after milling. Keywords: Al-B 4 C-Nanocrystalline; Al particle size; milling time; milling speed. 1. Introduction Aluminum metal matrix composites (AMCs) due to a number of suitable characteristics such as low density, high electrical and thermal conductivity, low thermal expansion and high temperature properties are being considered for numerous applications in aerospace and automotive industries, electronic packaging and sporting goods. 1 Recently, nonocomposites have attracted most attention for their unique properties. The mechanical properties of nano-metric dispersion strengthened MMCs are far superior to those of 2924 Int. J. Mod. Phys. B 2008.22:2924-2932. Downloaded from www.worldscientific.com by RUTGERS UNIVERSITY on 01/24/15. For personal use only.