Nano-structure evolution of secondary Al3(Sc1-xZrx) particles during superplastic deformation and their effects on deformation mechanism in Al-Zn-Mg alloys
Nano-structure evolution of secondary Al3(Sc1-xZrx) particles during superplastic deformation and their effects on deformation mechanism in Al-Zn-Mg alloys
复制标题
Al-Zn-Mg合金超塑性变形过程中二次Al-3(Sc1-xZrx)颗粒纳米结构演化及其对变形机制的影响
DOI：
10.1016/j.jallcom.2016.10.094
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发表时间：
2017-02-25
影响因子：
6.2
通讯作者：
Wang, Yingjun
中科院分区：
文献类型：
--
作者：
Deng, Ying;Yin, Zhimin;Wang, Yingjun
采用高分辨透射电镜研究了Al-3（Sc1-xZrx）在500℃高应变速率（0.01 s(-1)）超塑性变形过程中的纳米结构演变。结果表明：当真色度从0.69增加到2.40时，Al-3（Sc1-xZrx）颗粒的平均半径从9.8 +/- 3.4 nm增加到16.4 +/- 6.8 nm，晶格失配值从1.04%增加到1.30%；变形前，Al-3（Sc1-xZrx）纳米颗粒与Al(a)基体完全共融。随着变形的进行，累积的严重塑性变形在颗粒与基体界面处引入了错配位错。超塑性流动变形数据表明，随着真应变的增加，Al-Zn-Mg合金的应变速率敏感性从0.29降低到0.19，变形激活能从112增加到121 kJ/mol。而对于含有次级Al3（Sc1-xZrx）纳米颗粒的Al-Zn-Mg合金，应变速率敏感性从0.33提高到0.45，变形激活能从107降低到84 kJ/mol。根据显微组织结果和建立的不同应变下的本构方程，可以得出在加工硬化阶段，两种合金均受位错粘滑蠕变机制控制。在动态软化阶段，Al-Zn-Mg合金以位错蠕变机制为主，而Al-Zn-Mg- sc - zr合金以晶界滑动机制为主。二次Al-3（Sc1-xZrx）纳米颗粒对加速Al-Zn-Mg合金晶界协同变形具有重要作用，仅影响Al-Zn-Mg合金的动态软化变形机制。(C) 2016 Elsevier B.V.版权所有
The nano-structure evolution of secondary Al-3(Sc1-xZrx) particles during high-strain-rate (0.01 s(-1)) superplastic deformation at 500 degrees C was investigated by high resolution transmission electron microscopy. The results show that by increasing the true stains from 0.69 to 2.40, the mean radii of spheroidal secondary Al-3(Sc1-xZrx) particles increase from 9.8 +/- 3.4 nm to 16.4 +/- 6.8 nm, and the lattice misfit value increases from 1.04% to 1.30%. Before deformation, Al-3(Sc1-xZrx) nano-particles are completely coherent with Al(a) matrix. As the deformation proceeds, the accumulated sever plastic deformation introduces misfit dislocations at the interface between particles and matrix. Superplastic flow deformation data indicate that with the increase of true strains, the strain rate sensitivity of Al-Zn-Mg alloy decreases from 0.29 to 0.19, and the deformation activation energy increases from 112 to 121 kJ/mol. However, for Al-Zn-Mg alloy with secondary Al3(Sc1-xZrx) nano-particles, the strain rate sensitivity increase from 0.33 to 0.45, and the deformation activation energy decreases from 107 to 84 kJ/mol. Based on the microstructural results and the established constitutive equations at different strains, it can be concluded that at the working hardening stage, two kinds of alloys are both controlled by dislocation viscous glide creep mechanism. At the dynamic softening stage, dislocation creep mechanism operates in Al-Zn-Mg alloy, whereas grain boundary sliding mechanism is dominant in Al-Zn-Mg-Sc-Zr alloy. Secondary Al-3(Sc1-xZrx) nano-particles play an important role in accelerating the cooperative grain boundary deformation and only affect dynamic softening deformation mechanism of Al-Zn-Mg alloys. (C) 2016 Elsevier B.V. All rights reserved.