Structural features of mechanically alloyed Al-PbO and Al-PbO-WO3 composites

Mechanical alloying, cold compression and hot extrusion were used to prepare Al-PbO-WO3 and Al-PbO composites. The as-extruded and annealed samples were examined by means of transmission electron microscopy and X-ray analysis. Heavily deformed matrix containing very fine particles of basic components and some remaining Al-grains were observed in the as-extruded materials. Because of high affinity of oxygen to aluminum the heavily deformed matrix was chemically unstable on annealing at high temperatures. A thin Al-oxide layer around W-rich particles resulted from chemical reaction between aluminum matrix and WO3-particles in samples annealed for 1-2 h at 873 K. Reduction of PbO-particles within the Al-matrix was found to result in growth of cavities and coarsening of Pb-particles within pores. Colonies of very fine oxides within pores and Pb-particles located close to neighboring Al-matrix were often observed in annealed samples. (C) 2002 Elsevier Science B.V. All rights reserved.