Dimensional stability and thermal stress of 6061 Al/SiC w composite during thermal cycles

Abstract

The variations of dimensions and thermal stress of 6061Al/20 vol.-%SiC_w composites were investigated during thermal cycles between 25 and 300°C. Testing results showed that the dimensional stability and thermal stress are mainly related to the whisker distribution in the composite. For the as cast composite, owing to the whiskers being oriented randomly, the temperature cycles hardly affect the dimensions of the specimen, so this material has good dimensional stability. However, for the as extruded composite, owing to whisker alignment, the thermal cycles can evidently affect the dimensions of the specimen, i.e. the dimension is elongated in the alignment direction of whiskers and shortened in another direction. The dimensional stability of the as extruded composite can be improved somewhat by thermal precycles.