Influence of severe plastic deformation on dynamic strain aging of ultrafine grained Al-Mg alloys

本研究的目的是：1）探索SPD工艺对UFG Al-Mg合金的DSA和PLC效应的影响; 2）探索DSA和PLC效应对SDP处理的UFG Al-Mg合金变形行为的影响。在第一阶段期间进行的研究揭示了在室温下外部SPD处理对DSA的强烈影响和内部DSA效应对SPDed UFG Al-Mg合金的变形行为的强烈影响（参见本申请第1节中列出的第一阶段的工作报告和项目相关出版物[1]）。为了更深入地了解这些复杂的相互作用，必须在第二阶段进行基于实验结果的理论分析。为此，最近开发的模型DSA在粗晶粒/小应变FCC合金和应变硬化在非常大的应变FCC金属和合金将被利用。然而，它们必须被修改，以考虑到急剧细化的晶粒尺寸，严重增加的位错密度，因此，增强的溶质扩散性在作为SPD的Al-Mg合金。微观结构，力学和热力学数据，这是必要的模型修改将采取从实验结果。因此，在第二阶段，实验研究将从室温扩展到高温（分别为50 °C、100 °C、200°C和300 °C）。通过智能化的微观组织和力学实验研究，可以获得超快凝固Al-Mg合金在高温下的微观组织演变和力学行为，以及控制超快凝固强度和动力学的热力学参数，如溶质扩散系数、变形激活能/溶质原子间结合能和被抑制的移动的位错。在理论模型预测和实验结果的基础上，将建立在室温至300 °C的温度和10-5s-1至10-3s-1的应变速率下UFG Al-Mg合金（例如Al-1 Mg和Al-5 Mg）中限制DSA/PLC效应范围的相应域。

The purpose of the proposed project are 1) to explore the influence of SPD processing on DSA and the PLC effect of UFG Al-Mg alloys and 2) to explore the influence of DSA and the PLC effect on the deformation behavior of SDP-processed UFG Al-Mg alloys. Investigations carried out during the first period revealed a strong influence of both extrinsic SPD processing on DSA and intrinsic DSA effect on the deformation behavior of as-SPDed UFG Al-Mg alloys at room temperature (see the work report and the project-related publication [1] for the first period listed in the section 1 of this application). In order to gain a deeper physical insight into these complex mutual interactions, performed theoretical analysis based on the experimental results must be conducted in the second period. For this purpose, recently developed models for DSA in coarse grained/small strained FCC alloys and strain hardening at very large strains of FCC metals and alloys will be utilized. However, they have to be modified to account for the drastically refined grain size, the severely increased dislocation density and consequently, an enhanced solute diffusivity in the as-SPDed Al-Mg alloys. The microstructural, mechanical and thermodynamic data which are necessary for the model modifications will be taken from the experimental results. Therefore, in the second period the experimental investigations will be extended from RT to elevated temperatures (at 50 °C, 100 °C, 200°C and 300 °C, respectively). The information of microstructural evolution and mechanical behavior of as-SPDed UFG Al-Mg alloys at elevated temperatures, as well as thermodynamic parameters that control the DSA intensity and kinetics, like solute diffusivity, deformation activation energy/binding energy between solute atoms and arrested mobile dislocations, will be obtained by the intelligent microstructural and mechanical experimental investigations. The respective domain that limits the range of DSA/PLC effect in the UFG Al-Mg alloys (e.g. Al-1Mg and Al-5Mg) at the temperatures from RT to 300 °C and at the strain rates from 10-5s-1 to 10-3s-1 will be built on the basis of the theoretical model predictions and experimental results.