Hot deformation behavior of rare earth magnesium alloy without pre-homogenization treatment

The behavior and structure evolvement of as-cast Mg-Gd-Y-Nd-Zr magnesium alloy during the hot deformation process were discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.002-1 s(-1) and the temperature range of 573-723 K was researched on Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results show that the relationship between stress and strain is obviously affected by the strain rate and deformation temperature. The important softening mechanisms are eutectic melting and discontinuous dynamic recrystallization (DDRX) during deformation. The fragments of eutectic melting along the boundaries can turn round so as to take effect of the slippage between grains. The flow stress of Mg-7Gd-5Y-1.2Nd-Zr magnesium alloy during high temperature deformation can be represented by a Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The strain coefficient n and deformation activation energy Q are evaluated by linear regression analysis. A, a and n in the analytical expressions of sigma are fitted to be 2.401 93x10(15), 0.017 3 MPa-1 and 3.218 19, respectively. The hot deformation activation energy of alloy during hot deformation is 234.950 58 kJ/mol. The results also show that the structure of primitive microstructure has an effect on the plastic deformation.