Influence of extrusion temperature on the aging behavior of 6061Al-15vol%SiCw composites

Abstract

It is known that some discontinuously reinforced metal matrix composites, MMCs, with precipitation hardenable matrices, like 6061Al with SiC whiskers or particles, show faster aging behavior than the unreinforced alloys. Regarding the influence of processing techniques on the aging behavior, some investigations have found acceleration on aging of materials consolidated by powder metallurgy (PM) with respect to materials consolidated by ingot metallurgy (IM). This was attributed to the higher presence of oxide inclusions in the PM than in the IM materials. For a given composite preparation technique, however, the influence of the processing variables on the aging response has been barely studied. In this work, the effect of extrusion temperature on the aging of 6061Al-15vol%SiC{sub w} composites processed by a powder metallurgy route is investigated. The results obtained in this research go deep into the influence of the dislocation density on both the accelerated aging and the increase in strength of composites. Whereas the effect of dislocation density on accelerated aging is well documented, its effect on the strength of MMCs is not yet clear.