Hot Compression Behavior and Constitutive Model of Dilute Mg-Sn-Y Alloy

A small amount of the second phase with excellent thermal stability can be used as an important strengthening phase in Mg-Sn-Y alloy system. In order to study the influence of trace alloying elements on the hot deformation behavior of Mg-Sn-Y alloy, Mg-0.4Sn-0.5Y alloy with low alloy content was melted and cast in this paper. The flow stress−strain behavior of MG-0.4Sn-0.5Y alloy during hot deformation was studied by thermodynamic simulation test. Linear regression analysis, metallographic analysis (OM), scanning electron microscopy (SEM) and other methods were used to study the relationship between flow stress, deformation temperature and strain rate during the hot compression deformation of the alloy. The constitutive model was constructed to analyze the thermal deformation behaviors, such as deformation activation, combined with the microstructure evolution. The results show that the flow stress and strain curves of Mg-0.4Sn-0.5Y alloy have obvious dynamic recrystallization characteristics under hot compression deformation at strain rates of 1×10−2−1×10−4 s−1 and deformation temperatures of 300~450 ℃. The relationship among flow stress, deformation temperature and strain rate satisfies the hyperbolic sinusoidal modified Arrhenius formula proposed by Sellars and Tagert. It satisfies the flow stress constitutive equation: Ε =1.555×1011 [sinh(0.0261σ)]3.665exp [−183656.7/RT], and the deformation activation energy of the alloy is higher than that of the ordinary magnesium alloy. The reason is that there are diffusely-distributed particle second phases and more long rod and strip second phases in the matrix, which hinder the cross-slip and climbing of dislocations, thus increasing the energy required for dislocation initiation and resulting in the increase of the activation energy of alloy deformation. © 2024 Editorial Office of Chinese Rare Earths. All rights reserved.