Cooling rate induced radial gradient structure in cylindrical metallic glasses

The mechanical property dependence of a typical Zr52·5Cu17.9Ni14·6Al10Ti5 metallic glass on micro-structure has been investigated using nanoindentation. Heat flow equation was chosen to study cooling rate and the micro-structure during the casting process. Results show that cylindrical sample with larger dimension possesses a lower cooling rate, which leads to larger elastic modulus and higher hardness accordingly, and so is the center region compared to boundary in the cross section of a cylindrical specimen. To a certain extent, cylindrical metallic glasses are radial gradient structure induced by the cooling rate in a small range.