Composite layers containing ~0.8 %vol Al2O3 nanoparticles were produced on AZ91 magnesium alloy by friction stir processing (FSP). The treated layers were characterized using optical and scanning electron microscopes, as well as microhardness and wear testing units. It was noticed that, by reducing the rotational speed and increasing the travel speed, the grain size of the treated layer reduces and its hardness increases. In addition, the presence of nano Al2O3 reduces the grain sizes of the layers further and increases their hardness. Furthermore, FSP of AZ91 with Al2O3 particles improved the wear resistance significantly and changed the wear mechanism from oxidation and adhesive mode in the as-received AZ91 to oxidation and abrasive in the FSPed specimens. Finally, the rotational speed of 800 rpm and the travel speed of 40 mm/min were the optimum parameters for achieving a suitable composite layer with the highest hardness and wear resistance among the treated layers

Graphene–NiFe₂O₄–carbon nanocomposites with a sandwich structure are synthesized via the hydrothermal growth of NiFe₂O₄ nanoparticles on graphene sheets, followed by carbon coating. As a promising anode material for Li ion batteries, the nanocomposites deliver exceptional cycle stability of 1195 mA h g⁻¹ after 200 cycles measured at 500 mA g⁻¹. This value is among the highest reported so far for anodes containing similar NiFe₂O₄ nanoparticles. The synergy arising from the conductive graphene substrate, the well-dispersed, ultrafine NiFe₂O₄ nanoparticles and the protective carbon layer sustaining the sandwich together is responsible for this trait.