Thermal stability and crystallization of Zr-Al-Cu-Ni based amorphous alloy added with boron and silicon

The amorphous Zr65-x-yAl7.5 Cu17.5Ni10SixBy alloy ribbons, x=1-4 and y=1-2, with 0.1 mm thickness were prepared by melt spinning. The thermal properties and microstructure development during the annealing of amorphous alloys were investigated by the combination of differential thermal analysis, differential scanning calorimetry, X-ray diffractometry, and TEM. Both of the glass transition temperature and the crystallization temperature for Zr65-x-yAl7.5 Cu17.5Ni10SixBy alloys increases with the silicon and boron additions and reaches 674 and 754 K, respectively for Zr60Al7.5 Cu17.5Ni10Si4B1 alloy. The highest T-rg (0.62) and gamma value (0.43) occurred at the Zr60Al7.5Cu17.5Ni10Si4B1 alloy. In addition, the Zr60Al7.5Cu17.5Ni10Si4B1 alloy was revealed to have the highest activation energy of crystallization (about 370 kJ/mol as determined by the Kissinger plot). This value is about 20% higher than the activation energy of crystallization for the Zr65Al7.5Cu17.5Ni10 based alloy (314 kJ/mol). In parallel, the alloy 4Si1B also performs a longer incubation time at higher isothermally annealing temperature. All of the evidence implies that Zr60Al7.5 Cu17.5Ni10Si4B1 alloy exhibits the highest thermal stability among those alloys in this study. The crystallization behavior for the alloy 4Si1B isothermally annealed at the supercooled temperature region for different time has also been examined by TEM and discussed. (c) 2006 Elsevier Ltd. All rights reserved.