On the Hardening of Friction Stir Processed Mg-AZ31 Based Composites with 5–20% Nano-ZrO₂ and Nano-SiO₂ Particles

抄録

Mg-AZ31 based composites with 10–20 vol% nano-sized ZrO₂ and 5–10 vol% nano-sized SiO₂ particles were fabricated by friction stir processing (FSP). The clusters of the nano-ZrO₂ and nano-SiO₂ particles, measuring 180–300 nm in average, were relatively uniformly dispersed. The average grain size of the Mg matrixes of the composites varied within 2–4 μm after four FSP passes. No evident interfacial product between the ZrO₂ particles and Mg matrix was found during the FSP mixing ZrO₂ into Mg-AZ31. However, significant chemical reactions occurred at the Mg/SiO₂ interface to form the Mg₂Si phase. The mechanical responses of the resulting nano-composites in terms of hardness and tensile properties of these Mg/nano-ZrO₂ and Mg/nano-SiO₂ composites were examined and compared. The grain refinements and the corresponding hardening mechanisms are also analyzed and discussed.