Abstract
In this study the hybrid effect on the orientation dependence of the composite strength of an aluminum cast alloy reinforced by AL_2O_3 whiskers and SiC particles is studied experimentally and numerically. The monotonic strength is higher when the hybrid MMCs is subjected to the external load parallel to the random whisker orientation in plane than those when the load is perpendicular to the whisker orientation. The whisker orientation dependence of composite strength in the hybrid composite is weaker than the one in the whisker reinforced composite. On the fracture surface of the specimen loaded along parallel direction to the random whisker orientation in plane broken whiskers are the majority while a lot of de-bonded interfaces between whisker and matrix are observed on the fracture surface of the specimen loaded along perpendicular direction to whisker orientation. To characterize the hybrid effect on the whisker orientation dependence of composite strength, a three-dimensional hybrid composite unit cell model including whiskers and particles is developed using finite element method.
