Influence of extrusion temperature on the microstructure and the texture of 6061Al-15 vol. % SICwPM composites

A systematic study of the microstructure and the texture of powder metallurgy, PM, 6061Al metal matrix composites, MMCs, as influenced by the extrusion temperature, has been conducted. For this purpose, a containerless PM route has been developed to controlling the parameters involved during processing of materials. A strong fiber texture with two components: <111> and <100>, (with the fiber axis parallel to the long extrusion direction) is developed in the matrix of all materials. A limited particle stimulated nucleation process, PSN, occurs during extrusion of the composites when the extrusion temperature, T-extr, is low. The SiC in the composites is divided in two populations; whiskers oriented with the extrusion axis (oriented whiskers) and randomly oriented whiskers (random whiskers) plus particles. Whereas the average whisker length does not change significantly with T-extr, the "degree" of alignment of oriented whiskers (which follows a Gaussian distribution function) is clearly accentuated in the composites extruded at high T-extr with respect the composites extruded at low T-extr. (C) 2002 Elsevier Science Ltd. All rights reserved.