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 2 h under 140 MPa, in which MWCNTs provide a high reinforcement factor of 0.6 and a yield stress of 2.2 GPa at the 4 vol% 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 450 MPa at the 8.3 vol% 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 280 MPa at the 9.2 vol% 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.