Sadeghi Behzad, Cavaliere Pasquale, Nosko Martin, TremboŠovÁ Veronika, Nagy Štefan
State Key Laboratory of Metal Matrix Nanocomposites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
Department of Innovation Engineering, University of Salento, Lecce, Italy.
J Microsc. 2021 Jan;281(1):28-45. doi: 10.1111/jmi.12947. Epub 2020 Aug 5.
The deformation behaviour of bimodal sized Al O /Al nanocomposites were investigated by hot compression tests conducted in the temperature range 350-500°C and strain rates of 0.001, 0.01 and 0.1 s . The dynamic recrystallisation behaviour of the nanocomposites strongly depended on the forming parameters. The bimodal sized Al O particles played a crucial role in the recrystallised microstructure. The addition of bimodal sized Al O particles led to a significant increase of activation energy of plastic deformation, corroborating the enhanced resistance of the nanocomposite to hot deformation. This was also reflected by the increased compressive yield strength in the nanocomposite due to both dislocation strengthening caused by n-Al O and preventing the grain growth due to the presence of μ-Al O at grain boundaries. It was found that with the decrease of Z values, local strain induced by deformation was released and the grain size of aluminium matrix gradually increased, indicating that the main softening mechanism of the bimodal sized Al O /Al nanocomposites was dynamic recrystallisation (DRX). The lower the Z value was, the easier the DRX occurred. The highly beneficial role of the bimodal sized Al O reinforcement in improving the high-temperature performance of aluminium matrix nanocomposite was discussed.
通过在350 - 500°C温度范围内进行热压缩试验，并在应变速率为0.001、0.01和0.1 s⁻¹的条件下，研究了双峰尺寸的Al₂O₃/Al纳米复合材料的变形行为。纳米复合材料的动态再结晶行为强烈依赖于成形参数。双峰尺寸的Al₂O₃颗粒在再结晶微观结构中起着关键作用。双峰尺寸Al₂O₃颗粒的添加导致塑性变形激活能显著增加，证实了纳米复合材料对热变形的增强抗性。这也反映在纳米复合材料中压缩屈服强度的增加上，这是由于n - Al₂O₃引起的位错强化以及晶界处μ - Al₂O₃的存在阻止了晶粒生长。研究发现，随着Z值的降低，变形引起的局部应变得以释放，铝基体的晶粒尺寸逐渐增大，这表明双峰尺寸的Al₂O₃/Al纳米复合材料的主要软化机制是动态再结晶（DRX）。Z值越低，DRX越容易发生。讨论了双峰尺寸Al₂O₃增强相在改善铝基纳米复合材料高温性能方面的高度有益作用。
