Surface Characteristics Improvement of AZ31B Magnesium by Surface Compositing with Carbon Nano-tubes through Friction Stir Processing


Department of Materials Engineering, Isfahan University of Technology, Iran


In this research, the compositing of the surface of AZ31B magnesium alloy with CNT was studied by FSP. The parameters under study were rotational speed (500-1500 rpm), transverse speed (12-44 mm/min), number of passes (1-4), and CNT weight fraction (0-2%). Microhardness testing, optical metallography, FESEM, and EDS analysis were employed for the characterization of the samples. The suitable limits for the transverse speed and rotational speed were 12-24mm/min and 870-1140 rpm, respectively. The highest hardness in the FSP without compositing was assigned to the transverse speed of 24 mm/min and rotational speed of 870 rpm with a hardness of about 60 Vickers and the stir region grain size of less than 5 microns. The Zener-Holman parameter was calculated for computation and the least value was related to the conditions of the transverse speed of 12-24 mm/min and rotational speed of 870 rpm; as a result, the samples with the finest grain size were theoretically and experimentally specified. The most homogenous structure with the highest hardness was related to the three-pass state with a hardness of 69 Vickers. The best rate was the CNT weight percentage with a %2 weight enjoying the highest hardness. The FESEM images confirmed the suitable distribution of CNTs in the background after the performance of the three-pass processing.


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