Influence of extrusion temperature on the microstructure and the texture of 6061Al–15 vol.% SiCw PM 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, Textr, 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 Textr, the “degree” of alignment of oriented whiskers (which follows a Gaussian distribution function) is clearly accentuated in the composites extruded at high Textr with respect the composites extruded at low Textr.