Metal matrix composites (MMCs) can be tailored to produce various combinations of stiffness and strength and have found a wide range of applications where existing materials are not suitable for use in automotive and aerospace industries and many other areas. A key challenge for fabricating nanoparticle reinforced MMCs is to overcome the strong tendency of particle agglomeration. The present work was carried out to investigate the effect of high shear treatment on the microstructure and mechanical performance in the fabrication of magnesium and aluminium alloy matrix particulate nanocomposites. In particular, the impact of high shear treatment on reinforcing particle distribution and consequently microstructure and mechanical performance was examined. An Mg-2Zn-0.5Ca alloy and commercially pure aluminium were selected as the matrix alloys. Hydroxyapatite nanoparticles (~50nm, spherical, 1-5wt%) were added to the magnesium alloy as reinforcing elements and alumina nanoparticles (~30nm, spherical, 1-3wt%) to aluminium. The high shear treatment was employed after the admission of reinforcing particles by mechanical stir and performed with a rotor-stator device at a speed of ~5000rpm. Microstructure and particle distribution was characterized using optical and electron microscopy assisted with EDAX and EBSD techniques. Mechanical performance was assessed by standard compression and tensile testing. Experimental results showed that the high shear treatment effectively reduced particle agglomeration for both Mg/HA and Al/Al2O3 nanocomposites and enhanced both yield strength and ultimate strength without a significant reduction in ductility. The mechanical performance was further improved upon plastic deformation by hot extrusion and cold rolling respectively.

Dr Yan Huang leads metallic biomaterials and metal matrix nanocomposites research at Brunel University London, with interests in structural and biomedical applications. He is a founding member and co-investigator of the UK government EPSRC Future Liquid Metal Engineering HUB where he leads the activities on light alloy processing involving both solidification and plastic deformation. He has extensive experience in process innovation for combined solidification and thermomechanical processing, solid state joining and severe plastic deformation for light alloys and light metal matrix composites. He has long-term interests in the characterization of microstructure and texture evolution during thermomechanical processing and fundamental issues of strengthening, plastic deformation and grain boundary migration. He has published over 100 papers and filed 3 patents with an h-index of 22 and a total of 1865 citations.