X.J. Wang

Development of High Performance Magnesium Matrix Nanocomposites Using Nano-SiC Particulates as Reinforcement

In the present study, magnesium-based composites with three different volume percentages of nano-sized SiC particulates (SiCp) reinforcement were fabricated using a simple and inexpensive technique followed by hot extrusion. Microstructural characterization of the materials revealed uniform distribution of nano-size SiCp and obvious grain refinement. The tensile test result indicates a remarkable improvement on the strength for the as-extruded SiCp/AZ31B nanocomposite, while the elongation to fracture was decreased by comparing with the AZ31B alloy. Although, compared with the as-extruded AZ31B alloy, the ductility of the SiCp-reinforced AZ31B nanocomposite is decreased, but the ductility of the present SiCp-reinforced AZ31B nanocomposite is far higher than that of the conventional micron or submicron SiCp-reinforced magnesium matrix composites. It is concluded that, compared with the larger sized (micron or submicron) particles, the addition of nano SiCp in the AZ31B alloy resulted in the best combination of the strength and ductility. An attempt is made in the present study to correlate the effect of presence of nano-SiCp as reinforcement and its increasing amount with the microstructural and mechanical properties of magnesium.

Microstructure and Tensile Properties of AZ31B Alloy and AZ31B-SiCp Deformed Through a Multi-step Process

The 15 vol.% micron SiC particle (SiCp)-reinforced AZ31B magnesium matrix composite (AZ31B-SiCp) prepared with semisolid stirring-assisted ultrasonic vibration was subjected to a multi-step process. The influence of the multi-step processing route on the microstructure and mechanical properties of the AZ31B-SiCp was investigated. For comparison, the monolithic AZ31B alloy was also processed under the same conditions. The results showed that the grain sizes of the AZ31B alloy and the AZ31B-SiCp were gradually decreased with increasing the processing step. Compared with the AZ31B-SiCp, the grain size of the AZ31B alloy was much larger, and the grain size distribution was inhomogeneous at the same processing condition. The particles of the AZ31B-SiCp were dispersed uniformly through the multi-step processing. Moreover, the tensile properties of the materials were gradually improved with increasing the processing step. In particular, the strength of AZ31B-SiCp and the ductility of AZ31B alloy improved significantly based on the room-temperature tensile test results.