Search

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. [ABSTRACT FROM AUTHOR]

This study involves the investigation of the mechanical properties of the extruded tube products with reinforced silicon carbide particulates (SiCp). Finite element analyses are firstly conducted to analyze the plastic flow of the magnesium alloy AZ61 within the die and to investigate the effects of initial billet temperatures on the extrusion loads and final product temperatures. AZ61/SiCp composite ingots reinforced with different weight fractions of SiCp are fabricated by a melt stirring technique. A specially designed die set is used in the extrusion experiments to obtain tubes with uniform thickness distribution in the circumferential direction. The extruded tubes are also heat treated to obtain even better mechanical properties. Finally, tensile tests, Vickers microhardness, tests and microstructure observation are performed on the billets and extruded tubes of AZ61 monolithic alloys and AZ61/SiCp composites. A much smaller grain size and higher tensile strength and hardness are achieved for the extruded AZ61/SiCp composite tubes. [ABSTRACT FROM AUTHOR]