Progress in research on hybrid metal matrix composites

Hybrid metal matrix composites (MMCs) exhibit superior overall mechanical and functional response when compared to their conventional counterparts and as a result have greater potential to be widely used for structural engineering and functional device applications. This review focuses on the recent developments in the fabrication techniques and properties characterization of Al, Mg, Ti, Cu, Fe/steel and Ni matrix composites containing hybrid reinforcements. The hybrid reinforcements are classified according to different types, shapes and sizes. Novel processing techniques proposed for achieving homogeneous distribution of hybrid reinforcements and forming special structures are critically reviewed. The mechanical properties of various matrix systems are summarized and analyzed, while the strengthening mechanisms triggered by hybrid reinforcements are discussed. Meanwhile, a prediction model for yield strength of hybrid MMCs is also proposed. The effects of hybrid reinforcements and fabrication conditions on functional properties, including tribological, thermal, and electrical properties, of the hybrid composites are also described systematically. Finally, future work for promoting further development of this field is also addressed. •The hybrid reinforcements are classified and discussed in detail.•Novel processing techniques are critically reviewed.•The mechanical properties of various matrix systems are summarized and analyzed.•The strengthening mechanisms are discussed systematically.•Functional properties of the hybrid composites are also described systematically.