Liu Mao, Wang Pengfei, Lu Guoxing, Huang Cheng-Yao, You Zhong, Wang Chien-He, Yen Hung-Wei
School of Metallurgy, Northeastern University, Shenyang, 110819, China.
Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
iScience. 2022 Apr 14;25(5):104248. doi: 10.1016/j.isci.2022.104248. eCollection 2022 May 20.
Bulk aluminum rarely forms deformation or annealing twins owing to its high stacking fault energy. We report a novel twinning mechanism mediated by dynamic recrystallization in 6N pure aluminum under high strain rate (∼1.3 × 10 s) impact at a cryogenic temperature (77 K). Discontinuous dynamic recrystallization occurs during rapid severe plastic deformation and generates inhomogeneous microstructures exhibiting low-angle and high-angle grain boundaries. Unexpectedly, Σ3 twin boundaries were able to develop during dynamic recrystallization. Although these recrystallization twins have similar morphology as that of annealing twins, their formation relies on deformation activation instead of thermal activation, which was suppressed by the cryogenic experiment. Besides, strong orientation dependence was observed for formation of these novel twins. Beyond annealing and deformation twin, deformation-activated recrystallization twin is a new path for pure aluminum twinning.
块状铝由于其高堆垛层错能，很少形成形变孪晶或退火孪晶。我们报道了一种在低温（77 K）下，6N纯铝在高应变速率（约1.3×10⁵ s⁻¹）冲击下由动态再结晶介导的新型孪晶机制。在快速剧烈塑性变形过程中发生了不连续动态再结晶，并产生了呈现低角度和高角度晶界的不均匀微观结构。出乎意料的是，Σ3孪晶界能够在动态再结晶过程中形成。尽管这些再结晶孪晶与退火孪晶具有相似的形态，但其形成依赖于形变激活而非热激活，而低温实验抑制了热激活。此外，观察到这些新型孪晶的形成具有强烈的取向依赖性。除了退火孪晶和形变孪晶之外，形变激活再结晶孪晶是纯铝孪晶形成的一条新途径。
