Abstract

In this study, the samples of LA43M Mg–Li alloy were compressed to the true strains of 0.12, 0.16, 0.36 and 0.60 under 300 °C and the strain rate of 0.1 s⁻¹. Under this condition, the stress–strain curves present a special bimodal phenomenon at the early deformation stage, which is caused by twinning and dynamic recrystallization. In the process of hot compression, extension twins generated first. Twinning accommodated strain and the glide of twinning dislocations dissipated local strain energy, resulting in the first local stress drop. Then extension twins coarsened and devoured all the matrix, leading to the change of grain orientation. Subsequently, dislocations accumulated at the grain boundaries and resulted in the increase in stress. With further strain, dynamic recrystallization occurred, discontinuous dynamic recrystallization is the main dynamic recrystallization mechanism. The generation of dynamic recrystallization resulted in the strain softening and leaded to the second local stress drop. Twinning retards the occurrence dynamic recrystallization and has a crucial influence on the microstructure development during the hot compression of LA43M.

Graphic Abstract

中文翻译：

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LA43M Mg-Li合金热压缩过程中应力-应变曲线的双峰现象

摘要

在这项研究中，LA43M Mg-Li合金样品在300°C和0.1 s ^-1的应变速率下被压缩至真实应变为0.12、0.16、0.36和0.60。。在这种条件下，应力-应变曲线在变形的早期呈现出特殊的双峰现象，这是由孪晶和动态再结晶引起的。在热压缩过程中，首先产生延伸双胞胎。孪晶适应了应变，孪晶位错的滑移消散了局部应变能，导致了第一个局部应力下降。然后延伸孪晶粗化并吞噬了所有基质，导致晶粒取向发生变化。随后，位错在晶界处积累并导致应力增加。随着进一步的应变，发生动态再结晶，不连续的动态再结晶是主要的动态再结晶机理。动态再结晶的产生导致应变软化并导致第二局部应力下降。

图形摘要