INFLUENCE OF INTERMETALLIC PHASE’S ON THE FRACTURE SURFACES IN SECONDARY ALUMINIUM CAST ALLOY

Abstract

The contribution describes changes of the character of fracture surfaces depending on the morphology of intermetallic phases in secondary aluminium cast alloy. Morphology changes of intermetallic phases in recycled (secondary) aluminium cast alloy were depended on age-hardening. For study was used age-hardening. The age hardening consist of solution treatment at temperature 515°C with holding time 4 hours, water quenching at 40°C and artificial aging by different temperature 130°C, 170°C and 210°C with different holding time 2, 4, 8, 16 and 32 hours. Recycled (secondary) aluminium cast alloys containing more of additional elements that form various intermetallic phases in microstructure. It is therefore necessary to study structure of recycled aluminium alloy and influence of intermetallic phases. Intermetallic phases were observed by using of combination different analytical techniques (scanning electron microscopy - SEM upon black-white etching, deep etching and energy dispersive X-ray analysis - EDX) in microstructure. Heat treatment led to gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al 2 Cu). The changes of the morphology of intermetallic phases led to changes of fracture surface in recycled (secondary) aluminium cast alloy.