Single-layer graphene oxide reinforced metal matrix composites by laser sintering: Microstructure and mechanical property enhancement

This study investigates the integration of single-layer graphene oxide (GO) powders with iron matrix by laser sintering and its effects on mechanical strength and fatigue life. A laser-based additive manufacturing process is used to sinter GO and iron powders, and form GO Fe nanocomposite materials. The aggregation of GO powders was prevented by the fast laser heating and cooling process. In addition, the evaporation of polyvinyl alcohol, which acted as a dispersing agent, from the cross-section helps align the GOs vertically in the cross-section. An energy-dispersive X-ray spectroscopy map from cross-sectional scanning electron microscopy images and Raman patterns together demonstrate the reduction of GOs after laser sintering. The GO-matrix interfacial structure was investigated by transmission electron microscopy. GOs were found to be stretched due to the rapid heating and cooling process during laser irradiation. Strengthening mechanisms of tensile strength and Young's modulus were developed based on the laser sintering results. Surface microhardness was increased by 93.5% by laser sintering of 2 wt.% GO. The improvement in the fatigue life after laser sintering of GO-reinforced iron matrix nanocomposites was also investigated. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.