ON THE MECHANISM OF CREEP IN SHORT-FIBER-REINFORCED ALUMINUM-ALLOYS

The present work studies creep damage accumulation in a squeeze cast, short fibre reinforced aluminium alloy containing 15 vol.% of Saffil fibres. Fibre breakage occurs early in creep life. Individual fibres can undergo more than one rupture event. Primary and tertiary creep are closely related processes and cannot be considered as being independent. The minimum creep rate is a result of a superposition of load transfer from the matrix to the fibres (decrease of creep rate) and fibre breakage (increase of creep rate). In summary, creep of short fibre reinforced aluminium alloys is governed by three elementary processes including (i) loading of fibres through the formation of a work hardened zone around the fibres, (ii) a recovery mechanism in the work hardened zone, and (iii) the breakage of fibres into subfibres.