Failure Behaviors of 2D-C<sub>f</sub>/Mg Composites Fabricated by Liquid-Solid Extrusion Following Vacuum Pressure Infiltration

Abstract

Liquid-solid extrusion following vacuum pressure infiltration technique (LSEVI), which integrates melting, pouring, infiltration, and liquid-solid forming under high infiltration pressure, is a promising technique for the fabrication of metal matrix composite. LSEVI technology combines the advantages of both squeeze casting and gas pressure infiltration method. In this study, 2D carbon fiber reinforced AZ91D matrix composites (2D-Cf/Mg composites) were fabricated by LSEVI. Pyrolytic carbon (PyC) coating was deposited on surface of T700 carbon fiber by chemically vapour deposited (CVD) before fabrication. SEM observation indicated that the composites were well fabricated by LSEVI. The ultimate tensile strength of 2D-Cf/Mg composites fabricated by LSEVI was 390-410 MPa. Two kinds of failure behavior were found during tensile test: abrupt failure and progressive failure. The abrupt failure was characterized by a complete failure after the ultimate tensile strength (UTS) was reached. The progressive failure was a unique failure behavior with gradual damage after the UTS. In the case of progressive failure, the remaining strength after the UTS was 79% of the UTS. There was a remaining strength of 200 MPa under the strain of 0.1. Fracture surface morphology indicated that the remaining strength was attributed to the gradual breakage of the fiber bundles.