Synergistic Strengthening of Al Matrix Composites by in Situ Pyrolysis of C and Precipitation of Nanophases

Abstract

This study focuses on addressing the dispersibility issue of carbides in Al matrix composites through the in-situ pyrolysis of polymers. Furthermore, the addition of Ag enables Ag-C synergistic reinforcement of Al matrix composites, offering a novel reinforcement approach for Al matrix composites. The Al-16Ag-C composite is fabricated through the in-situ pyrolysis of PVB (Polyvinyl Butyral) followed by hot pressing sintering. Subsequently, the effect of temperature on the microstructural evolution and mechanical properties of the composite is investigated. The underlying strengthening mechanisms are also examined and discussed. Microstructural characterization demonstrates the formation of two alloy phases, namely Ag2Al and Al4C3, within the Al-16Ag-C composite. The formation of Al4C3 is dependent on the temperature utilized during sintering. The alloy phases, distributed at the grain boundaries, enhance the material’s strength by impeding dislocation motion, increasing dislocation density within the matrix, and limiting grain growth. The Al-16Ag-C composite, sintered at 630 °C, exhibits a remarkable ultimate tensile strength of 481 MPa and an elongation of 22.25%, representing a significant enhancement compared to pure aluminum.

Keywords: Al matrix composite, Hot pressing sintering, Ag2Al, Al4C3, Strengthening mechanisms