FATIGUE BEHAVIOUR OF SiC_p/6061Al COMPOSITE

The fatigue of SiC_p/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 10~7 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 SiC_p 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 are formed near interface and corner region of SiC_o in thecomposite subjected to fatigue stress(σ_(max)=274 MPa N=2.4×10~5 cycles),demonstratingthe relationship between fatigue crack initiation and dislocation movement in the SiC particlesreinforced 6061 Al alloy composite.