Hot compression behavior of Mg–Zn–Y–Mn–Ti magnesium alloy enhanced by lamellar LPSO phase and spherical W phase

Abstract

The hot compression experiments of the solution-treated Mg93.5Zn2.5Y2.5Mn1Ti0.5 alloy were carried out using a Gleeble-1500D thermal simulator under the conditions of a temperature of 350∼500 °C, a strain rate of 0.001–1 s−1 and a strain of 0.9. According to the stress-strain curve, the characteristics of flow stress were analyzed. Moreover, the constitutive equation of flow stress, the kinetic model of dynamic recrystallization, and the processing map were established. The results show that the flow stress of the alloy decreases as the deformation temperature increases or the strain rate decreases. The constitutive equation of flow stress can be expressed as a hyperbolic sine function: ε˙=4.27115×1019[sinh(0.01153σ)]8.493×exp(2.856×105/RT). With the increase of the deformation temperature or the decrease of the strain rate, the volume fraction and grain size of dynamic recrystallization of the alloy increase continuously. Its dynamic recrystallization volume fraction can be expressed by the Avrami equation as: XDRX=1−exp[−2.05((ε−εc)/ε∗)1.42]. The instability region of the alloy increases with the increase of strain. The first instability region is (350–410 °C, 0.12–1 s−1), the second one is (450–500 °C, 0.001–1 s−1), and the optimum domain for the hot processing of this alloy is (380–450 °C, 0.001–0.01 s−1).

Keywords

• Mg-Zn-Y-Mn-Ti magnesium alloy
• Constitutive equation
• Kinetic model
• Processing map