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The carbon fiber reinforced silicon carbide matrix (C/SiC) composites were prepared by using precursor infiltration and pyrolysis method. Fracture characteristics of C/SiC materials were studied by single edge notched beam with the aid of digital image correlation (DIC) technique. It was found that DIC played an important role in in-situ monitoring full/local strain evolution and cracking growth during bending tests, which was useful for revealing potential failure micro-mechanisms of C/SiC composites. The results showed that the average fracture toughness KIC and fracture strength of C/SiC were estimated as 7.81±0.12 MPa m1/2 and 223.23±3.5 MPa, respectively. Moreover, the crack extension resistance curves (R-curve) in terms of stress intensity (KR-curves) were determined on the basis of the crack initiation toughness KIC. The values varied from 4.68 MPa m1/2 to 16.83 MPa m1/2 during the R-curve tests. [ABSTRACT FROM AUTHOR]

Graphene oxide-carbon nanotubes hybrid reinforced aluminum matrix composites (GO-CNT/Al) were prepared by powder metallurgy followed by hot extrusion. The strength of the composites was improved by the synergistic effect of carbon nanotubes, in-situ Al 4 C 3 and graphene oxide. Moreover, due to the partially recrystallization of Al matrix promoted by Al 4 C 3 , the matrix exhibits a bimodal grain distribution, which helps to enhance strain-hardening and consequently uniform tensile ductility at high flow stresses. Hence the bimodal grain structure of the matrix combined with the nano-reinforcements leads to enhancing of the strength and ductility synergy. The composite shows a high tensile strength of 249 MPa (175 MPa of pure Al) and keeps almost similar tensile ductility with pure Al (uniform elongation of ~23.1%). • The structure changes of graphene oxide and carbon nanotubes during ball milling were revealed. • The influence of reinforcement dimension on the strengthening mechanism of aluminum matrix composites was emphasized. • The balance between strength and ductility is achieved by different dimension reinforcements and bimodal grain distribution. [ABSTRACT FROM AUTHOR]