High-strain-rate superplasticity of Zr_(65)Al_(10)Ni_(10)Cu_(15) sheet fabricated by squeeze casting method

摘要

The Zr_(65)Al_(10)Ni_(10)Cu_(15) alloy sheet produced by squeeze copper-mold casting method exhibited excellent superplasticity (a maximum elongation of 1350 percent) at a relatively high strain rate (2 X 10~(-2) s~(-1)) at 696 K. This achievement was made despite the occurrence of crystallization in the middle of deformation. Time for the onset of strain hardening could be related to the T.T.T. diagram for crystallization. Effect of holding time on flow stress was examined. As the holding time was longer, strain hardening took place earlier and the resulted fracture strain was smaller. Bulging test showed that the Zr_(65)Al_(10)Ni_(10)Cu_(15) alloy sheet could be deformed to near-net-shape by avoiding crystallization when fast heating rate and short holding time were applied.