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The microstructure, texture and mechanical property evolution of the extruded Mg- x Y (x = 1, 5 wt.%) alloys during equal channel angular pressing (ECAP) were systematically investigated using an optical microscope, electron backscatter diffraction (EBSD) and uniaxial tensile test. The Mg-Y alloys exhibited a weakened basal texture before the ECAP, and the texture was further weakened with the max basal poles dispersed along ∼45° between the extrusion direction and the transverse direction after the ECAP. The Mg-5Y alloys always exhibited a finer grain size comparing to that of Mg-1Y for the same ECAP process. With a proper ECAP process, both the strength and elongation of Mg-5Y alloy could be improved simultaneously after the ECAP, i.e., the yield strength (273.9 ± 1.2 MPa), ultimate strength (306.4 ± 3.0 MPa), and elongation (23.9 ± 1.0%) were increased by 10%, 6%, and 72%, respectively, comparing to that before the ECAP. This was considered to be arose from the combined effects of grain refinement, significant improved microstructure homogeneity and solid solution hardening. In addition, it was found that Mg-Y alloy with better comprehensive properties could be obtained by the decreasing-temperature ECAP processes. The yield strength-grain size relationship could be well described by the Hall-Petch relation for all the ECAPed Mg-Y alloys, which was consistent with that the texture changes did not significantly affect the average Schmid factors of basal, prismatic and pyramidal slips for both Mg-Y alloys. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]