Spontaneous Infiltration Behavior of Al Matrix into Carbon Fiber Bundles Induced by Al-Ni Binary Reaction

In this study, a Ni-coated carbon fiber reinforced Al-matrix (Ni-CF/Al) composite is prepared utilizing a pressure-free infiltration process. The CFs are coated with a layer of Ni through an electroless plating process, which facilitates the spontaneous infiltration behavior driven by the Al-Ni binary reaction. The spontaneous infiltration process, observed via synchrotron radiation in the direction opposite to gravity, demonstrates a fastest velocity of 31.02 ± 1.08 μm/s. By increasing the infiltration temperature, the interfacial microstructure of the composite can be enhanced, characterized by a reduction in un-infiltrated defects and promoted by the interfacial Al-Ni reaction. Notably, large-size Al-Ni intermetallic compounds (IMCs) at the interface are replaced by fine (Al+Al₃Ni) eutectic structure, given an optimal fabrication temperature of 720 °C. This contributes to a significantly enhanced ultimate tensile strength (UTS) of the composite, reaching a maximum of 135 ± 4 MPa, which is 159.6% higher than that of the matrix.