Microstructurally toughened particulate-reinforced aluminum matrix composites

Abstract

Silicon carbide particulate-reinforced aluminum matrix composites with dramatically higher energy absorption capability and damage tolerance have been demonstrated. The approach, referred to as microstructurally toughened composites, consists of segregating the composite into particulate-reinforced regions and continuous ductile toughening regions. Composites consisting of silicon carbide particulate-reinforced 6061 Al (SiCp/6061) with monolithic 6061 and commercially pure (CP) titanium toughening regions were fabricated. As much as an order of magnitude increase in notched Charpy impact energy absorption capability was demonstrated relative to conventional SiCp/6061 composites, with the higher values being associated with those samples that deflected the crack front more extensively during failure. The longitudinal tensile strength of the composites was shown to be independent of the scale of the microstructure or the magnitude of the toughening/reinforced region’s interfacial strength. The high impact energy 6061 toughened composites displayed low transverse tensile strength values, while the CP titanium toughened composites simultaneously displayed high energy absorption and high transverse tensile strength. A model was also developed to predict the minimum and maximum energy absorption capability of the composites, as well as provide a quantitative estimate of the composite energy absorption based on the measured crack front deflection length in the failed impact samples.