Qualitative and Quantitative Investigation of As-Cast and Aged CNT/AZ31 Metal Matrix Composites

Abstract

In this research, magnesium alloy AZ31 reinforced with CNTs (0 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.%) was produced by a stir casting method followed by aged heat treatment. Composites were investigated using x-ray diffraction and scanning electron microscope techniques. The microstructure of the CNTs/AZ31 has been qualitatively and quantitatively evaluated. The results show that stir casting is a suitable method for uniformly distributing CNTs and maintaining the integrated structure. The concentration of CNTs and aged heat treatment affects the crystallite size, crystallinity degree, precipitates and phase composition of the CNT-reinforced AZ31 alloy. An increase in the concentration of CNTs results in a decrease in the degree of crystallinity and dissolution of the secondary phase. In 0.1 wt.% CNTs, the crystallite size decreases and then increases. The aged heat treatment affects the composition of the phase and creates a new secondary phase to refine the microstructure and grain size. The compressive strength is linearly related to the concentration of CNTs. Bramfitt disregistry and precipitation strengthening play an important role in qualitatively and quantitatively refining and altering the microstructure of CNTs/AZ31.