Effect of the Addition of Nano-β-TCP on the Microstructure of Mg-Zn-Zr Alloy

In this study, a mental matrix composite (MMC) made of Mg-3Zn-0.8Zr alloy as a matrix and β-TCP particles as reinforcements were prepared for investigating the effect of β-TCP spherical particles sized in 100 nm on the microstructure of that alloy. The grains of as-cast or as-extruded Mg alloys systematically decreased from about 80 μm to about 30 μm with the choice of β-TCP contents. X-ray diffraction (XRD) analysis and optical microscopy (OM) observations show that the Mg-3Zn-0.8Zr-β-TCP (1.0 or 1.5, in wt %) composites were composed of various phases in addition to Mg and MgZn2 comparied with Mg-Zn-Zr alloy. New diffraction peaks appearing in the MMC, which suggests that a potential interaction occurred between β-TCP and the matrix. Transmission electron microscopy (TEM) images reveal that secondary phases, which wraps upon the surface of β-TCP, are uniformly distributed in the grains of Mg-Zn-Zr alloy. Energy spectrum analysis shows that the component of dark-colored parts is equivalent to β-TCP, but the component of light-colored parts is Mg-Zn-Ca, which demonstrates that there is a real interaction occurred between the matrix and β-TCP.