Cold plastic formability of aluminium-based MMCs

Substantial improvement in the cold formabilities of two Al-based MMCs manufactured by a P/M technique and stir casting have been found by suitable heat treatments, The two materials used were Al-2124/SiCp (17 vol.%, similar to 3 and similar to 13 mu m in diameter) and A356/SiCp (15 vol.%, similar to 16 mu m in diameter), When both materials were subjected to over-ageing treatments, they exhibited large plastic strains before fracture in compressive processes. A conventional closed-die forging was carried out on the Al-2124 MMCs as well as a backward can extrusion, Also bevel gears were manufactured from the A356 MMC, In each case the particles shattered and the matrix also contained cracks. These cracks were healed by peak ageing. This also improves the fatigue lives of the components.