Effect of strain rate on the compressive mechanical properties of aluminum alloy matrix composite filled with discontinuous carbon fibers

Compression and forced shear loading were utilized to investigate the quasi-static and dynamic response of carbon fiber/Al-Mg composites. Two types of carbon fibers (PAN-based (CPAN) and pitch-based (CPitch)) were introduced into an Al-Mg alloy matrix (∼30 vol% fibers). The CPAN/Al-Mg composite had higher compressive and shear strengths than CPitch/Al-Mg regardless of fiber orientation. The difference in strength due to the nature and probably quality of the fibers was more significant than the effect of fiber orientation (perpendicular or parallel to loading direction). The compressive strength of these composites exhibited a strain rate sensitivity comparable with that of an Al-Mg alloy and more pronounced for the CPAN/Al-Mg composite. The microstructural features of shear flow in the localized shear zone in hat-shaped specimens and the characteristics of fractured fibers are analyzed and discussed. Possible reaction of the metal matrix and carbon fibers was observed.