Dynamic stress-strain behavior in shear of SiCwhisker reinforced aluminum alloy composites

The strengthening effects in view of the dynamic mechanical properties of SiC whisker reinforced aluminum alloy composites are not well understood at present. The objectives of the present study are to determine the dynamic stress-strain characteristics of SiC/6061-T6 Al alloy composites and to analyze the strengthening mechanisms due to the SiC whisker reinforcement. A series of torsional impact tests was conducted on SiC/6061-T6 Al alloy composite specimens. The dynamic stress-strain was compared with the corresponding static stress-strain. The SiC/6061-T6 Al alloy composite displays a strain-rate sensitivity. A rapid decrease in the stress level of the static curve corresponds to fracture initiation within the gage length of the specimen. In contrast, there is a negligible amount of strain-rate sensitivity up to a shear strain rate of approximately 1700 per second. The strain rate dependence of the flow stress in the SiC/6061-T6 Al alloy composite is attributed to the dynamic interface interactions between the SiC whiskers and the matrix alloy.