The fatigue of SiCp/6061Al composite containing 15 v.-% SiC particles has been comparedwith 6061Al alloy.Dislocation structure and microprocess of fatigue crack initiation andpropagation in the composite have been investigated by using SEM and TEM.The results in-dicate that the fatigue strength at 107 cycles of the composite is 196 MPa,i.e.about 25%higher than matrix alloy.The voids and microcracks initiated at and near the interface be-tween SiCp and matrix,where has a higher density of dislocations,will propagate and link upto form the fatigue crack.It is an important evidence to note that the dislocation channelswhere screw dislocation can travel areformed near interface and corner region of SiCo in thecomposite subjected to fatigue stress(σmax=274 MPa N=2.4×105 cycles),demonstratingthe relationship between fatigue crack initiation and dislocation movement in the SiC particlesreinforced 6061 Al alloy composite.
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