Mechanical properties of Fe-based composites reinforced with multi-walled carbon nanotubes

Reinforcing efficiency of multi-walled carbon nanotubes (MWCNTs) has been investigated for Fe-based composites by powder metallurgy routes. For the mechanically milled Fe powder containing dispersed MWCNTs, first, the composite are produced by hot-pressing at 570°C for 2h under 140MPa, in which MWCNTs provide a high reinforcement factor of 0.6 and a yield stress of 2.2GPa at the 4vol% MWCNTs. On the other hand, for the composites produced by compaction and then sintering at 850°C, the dispersed MWCNTs decompose to be a Fe-C interstitial alloyed phase, in which the composite shows a relatively low yield stress of 450MPa at the 8.3vol% Fe-C phase. For the composite sintered at high temperature of 1150°C, the reinforcement factor is found to be 0.2 and a yield stress of 280MPa at the 9.2vol% Fe₃C. These results demonstrate that MWCNTs with a high aspect ratio and a strong bonding character with the matrix have a great role in reinforcing the Fe-based composites.