Superplastic gas pressure forming of Zr_(65)Al_(10)Ni_(10)Cu_(15) metallic glass sheets fabricated by squeeze mold casting

摘要

Superplastic gas pressure formability of the Zr_(65)Al_(10)Ni_(10)Cu_(15) bulk metallic glass (BMG) sheets was examined. Fabrication of large surface BMG sheets with fully amorphous structure and development of a special gas-blow-forming setup where oxidation and crystallization could be avoided during sample heating and forming were essential for this purpose. The sheets were produced by squeeze mold casting. The optimum pressure-time curve for formation of a hemisphere with a diameter of 22 mm was determined based on the analysis by finite element method and the experimental data obtained from tensile tests at 696 K for different strain rates. Gas pressure forming could be completed within 120 s as predicted by the FEM without introducing crystallization in any part of the final product.