FATIGUE BEHAVIOUR OF AL-12 % Si/SiC, COMPOSITE PRODUCED BY SQUEEZE CASTING TECHNIQUE

In the present work, the fatigue behaviour of a- 12% SiISiC,
composite containin (10% wt) Sic, particles have been compared with Al-
12% Si alloy. Dis f ocation structure and microprocesses of fatigue crack initiation and propagation in the composite have been investigated using SEM and TEM. The cyclic stress res onse characteristics and fkacture
behaviour of the composite were7also stu a ied. The obtained results showed
that the fatigue stren h at 10 cycles of the com osite is 1105 MP,, i.e.
about 28.6% higher t ff an matrix alloy. The voids an d' microcracks initiated
at and near the interface between Sic, and matrix, where the higher density dislocations are presented, will propagate and link up to form the fatigue crack. Cyclic response of the composite revealed hardening to failure at all
strain amplitudes. The fatigue fracture sf the composite exhibits a
macroscogical~y brittle characteristic at dl strain amplitudes, but has local matrix ductility.