The strength and thermal stability of Al–5Mg alloys nano-engineered using methods of metal forming

In this work, nano-engineering approach was used to increase the strength of Al-5 Mg alloys (5xxx series). These nano-engineering methods were: (a) plastic consolidation of powders at elevated temperature and (b) hydrostatic extrusion. The microstructural factors influencing their properties were characterised. The results indicate that the alloys can be significantly strengthened by both hydrostatic extrusion and consolidation of powders when compared to cold rolling. Both processing routes results in ultrafine grained structures which together with dislocation and solid solution strengthening bring about high strength (yield strength exceeds 400 MPa). In addition to efficient strengthening, plastic consolidations impart exceptional thermal stability, which can be attributed to the presence of nano-sized oxides and an increased fraction of high angle grain boundaries.