Powder Metallurgy Of Particle-Reinforced Aluminium Matrix Composites (Amc) By Means Of High-Energy Ball Milling

This paper deals with the production of aluminium matrix composites through high-energy milling, hot isostatic pressing and extrusion. Spherical powder of the aluminium alloy AA2017 (grain fraction > 100 mu m) was used as matrix material. SiC and Al2O3 powders of submicron and micron grain size (< 2 mu m) where chosen as reinforcement particles with contents between 5 and 15 vol.% respectively. The high-energy milling process was realised in a Simoloyer mill (Zoz). The milling time was about 4 hours. Hot isostatic pressing (HIP) was used to convert the compound powder into compact material. The extrusion process realises semi-finished products with different geometrical shapes.The stages of the composite powder formation during high-energy ball milling will be discussed by means of metallographic studies. The SEM and TEM results show the microstructure of the compact composites obtained by HIP and extrusion. This study focuses on the dispersion and embedding of reinforcement particles and matrix/reinforcement interfaces. Typical appearances like ferrous contaminations through abrasion of the steel balls and the formation of the spinel phase MgAl2O4 during the subsequent powder-metallurgical processing will be discussed. The semi-finished product exhibits a good particle dispersion and low microporosity. There are no accumulations of the brittle phases nor any microcracks at the interface between reinforcement particles and matrix.