Achieving improved mechanical performance in aluminum matrix composites with rebar-reinforced concrete-inspired structures.

Abstract

The strength of aluminum matrix composites (AMCs) often suffers from degradation at elevated temperatures, rendering them generally unsuitable for use in high-temperature environments. Inspired by ubiquitous rebar steel-reinforced concrete (RC) structures, we develop a series of RC-like AMCs by integrating the additive manufacturing and micro-casting methods. Such RC-AMC, with a high volume fraction of thermotolerant particulate reinforcements, effectively mitigate the strength degradation up to 500 °C. Through structural optimization, we demonstrate that such RC-AMCs achieve extraordinarily high compressive yield strength (up to 938 MPa) and specific strength (up to 235 kN·m/kg) at 400 °C - among the highest reported values for all the aluminum-based alloys and composites. The enhanced resistance to high-temperature softening in RC-AMCs is associated with abnormal thermal twinning in Al₃Ti when the temperature increases. This design strategy, combining anomalous temperature-dependent deformation behavior and multiscale reinforcing architectures, offers a pathway toward structure-material integrated manufacturing for a wide range of engineering alloys and composites.