The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy (LAZ1011) with a grain size of 3.2 µm, primarily composed of the BCC β phase and a small amount of the HCP α phase, were examined in a temperature range of 473 K to 623 K. The microstructural refinement of this alloy was achieved by employing high-ratio differential speed rolling. The best superplasticity was achieved at 523 K and at strain rates of 10⁻⁴ -5 × 10⁻⁴ s⁻¹, where tensile elongations of 550–600% were obtained. During the heating and holding stage of the tensile samples prior to tensile loading, a significant increase in grain size was observed at temperatures above 573 K. Therefore, it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and mechanisms. In the investigated strain rate range, the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding, while at high strain rates, lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation mechanism. It was concluded that solute drag creep is unlikely to occur. During the late stages of deformation at 523 K, it was observed that grain boundary sliding led to the agglomeration of the α phase, resulting in significant strain hardening. Deformation mechanism maps were constructed for β-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate, stress, temperature, and grain size, using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

晶粒尺寸为 3.2 µm、主要由 BCC β 相和少量 HCP α 相组成的细晶 Mg-10.1 Li-0.8Al-0.6Zn 合金 (LAZ1011) 的超塑性行为和相关变形机制，在 473 K 至 623 K 的温度范围内进行了检查。该合金的微观结构细化是通过采用高比差速轧制实现的。最佳超塑性在 523 K 和应变速率 10 ^-4 -5 × 10 ^-4 s ^-1下实现，拉伸伸长率为 550-600%。在拉伸加载之前拉伸样品的加热和保持阶段，在高于 573 K 的温度下观察到晶粒尺寸显着增加。因此，在分析和理解超塑性变形行为和机制时，考虑这种影响非常重要。在研究的应变率范围内，低应变率下的超塑性流动由晶格扩散控制的晶界滑动控制，而在高应变率下，晶格扩散控制的位错爬行蠕变是速率控制的变形机制。结论是不太可能发生溶质拖曳蠕变。在523 K变形后期，观察到晶界滑动导致α相团聚，导致显着的应变硬化。使用根据数据导出的各种变形机制的本构方程，以 2D 和 3D 格式构建了 β-Mg-Li 合金的变形机制图，作为应变率、应力、温度和晶粒尺寸的函数。当前的测试。