Achieving high strength and ductility in GNSs/Mg nanocomposites fabricated by in-situ liquid metallurgy combined with hot extrusion

The mechanical properties and processing scale of metal matrix nanocomposites are urgently desirable for engineering application. In this work, a novel production method of graphene nanosheets (GNSs) reinforced magnesium (Mg) matrix nanocomposites was developed by in-situ liquid metallurgy combined with hot extrusion. GNSs were dispersed and modified into Mg matrix effectively via in-situ chemical reaction between CO₂ and liquid Mg melt. The grain size of the as-extruded nanocomposites was dramatically refined because the GNSs facilitated retention of high dislocation density and the rotation of subgrain. The strength and ductility of the nanocomposites achieved a good balance at the extrusion temperature of 300 ℃. The strength of the nanocomposites depends mainly on the fine grain strengthening and load-transfer strengthening due to the in-situ grown GNSs. This novel method of metal matrix nanocomposites is suitable for mass production, which could be easily generalized to engineering applications.