Abstract

Mechanisms of grain refinement under multidirectional isothermal forging (MIF) at 325 °C (~ 0.65 T_m) and the strain rate 10^− 4 s^− 1 of the Al–Mg-based alloy with complex additions of transition metals were investigated. The starting alloy had an equiaxed grain structure with grain size 25 µm and a uniform distribution of coherent Al₃(Sc,Zr) dispersoids of 20–50 nm. A distinguished structural feature in the early MIF stage was the formation of high strain- and misorientation gradients, followed by deformation banding. Due to the sequential changes of the loading axis, such bands were developed in various directions and fragmented the original grains. The number of bands and misorientation of their boundaries gradually rose with strain, resulting in formation of (ultra)fine grain structure with the grain size 2 µm. New grain formation was concluded to occur via continuous dynamic recrystallization and controlled by the nanosized precipitates, which preferably remained stable and coherent with the surrounding matrix.

Graphic Abstract

中文翻译：

---

高温多方向等温锻造Al-Mg-Mn-Sc-Zr合金中超细晶粒结构的发展

摘要

下多向等温锻造（MIF）在325℃（〜0.65Ť晶粒细化机制_米）和应变率10 ^{4 -} 小号^{- 1}与过渡金属的复数加法所述Al-Mg系合金的进行了研究。起始合金具有等轴晶组织，晶粒尺寸为25 µm，且相干Al ₃均匀分布（Sc，Zr）20–50 nm的弥散体。MIF早期的显着结构特征是高应变和取向差梯度的形成，然后是变形带。由于加载轴的顺序变化，这些条带在各个方向上形成并破碎了原始晶粒。带的数目和边界的取向错误随着应变而逐渐增加，导致形成晶粒尺寸为2μm的（超）细晶粒结构。结论是通过连续动态重结晶发生了新的晶粒形成，并受到纳米级沉淀物的控制，这些沉淀物优选保持稳定并与周围的基体保持一致。

图形摘要