Superplastic Flow Behavior of Zr Base Bulk Metallic Glass in Supercooled Liquid Region
Zr基块体非晶合金在过冷液相区的超塑性流变行为

Isothermal tensile tests of Zr_(41.25) Ti_(13.75) Ni_(10)Cu_(12.5)Be_(22.5) bulk metallic glass in supercooled liquid region are carried out at four characteristic temperatures of 616, 636, 656 and 676 K which are in the vicinity of the end temperature of glass transition. Experimental results indicate that the superplastic flow behaviors of the material, viz., the flow stress and the elongation depend strongly on the testing temperature and tensile rate. The elongation increases firstly and then decreases with increasing rate and the maximum elongation reaches 1625% at 656 K and 5 mm/min. The strain rate sensitivity exponents determined by using Backofen method are 0.25, 0.65 and 0.93 at 636, 656 and 676 K, respectively. The free volume model is used to interpret the observed superplastic flow behavior.