Mechanical properties and microstructure of twin roll cast Al–7Si/SiC p MMCs

Unreinforced A356 alloy (AI–7Si) and A356 metal matrix composites (MMCs) reinforced with 10 and 20 vol.-%SiC particles have been manufactured by twin roll casting, and the resulting sheet tensile mechanical properties evaluated after a variety of different heat treatments. The SiC particles show a more uniform distribution in the roll cast sheet than in the MMC feedstock, and centreline macrosegregation of eutectic Si is less marked thanfor the roll cast A356 alloy. After solution heat treatment the ductility ofunreinforced A356 and MMCs are both increased, which is beneficialfor subsequent secondary fabrication. Roll cast 10 vol.-%SiC MMC reaches the peak aged condition after 5 h at 155°C, compared with 11 hfor the unreinforced A356. Compared with the as cast strip, the peak aged MMC exhibits greater proof stress and ultimate tensile strength (UTS), although its ductility is similar. Prolonged aging for 11 h slightly improves ductility, without significantly reducing proof stress or UTS.

MST/3058