Influence of severe plastic deformation on dynamic strain aging of ultrafine grained Al-Mg alloys
Influence of severe plastic deformation on dynamic strain aging of ultrafine grained Al-Mg alloys
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DOI：
10.1016/j.actamat.2014.05.004
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发表时间：
2014-09-01
期刊：
影响因子：
9.4
通讯作者：
Gottstein, Guenter
中科院分区：
文献类型：
--
作者：
Zhao, Shiteng;Meng, Chenlu;Gottstein, Guenter
研究了剧烈塑性变形（SPD）对不同Mg含量的超细晶Al-Mg合金动态应变时效（DSA）的影响。在室温下进行的受限通道模压（CCDP）用于SPD。TEM微观表征显示，显着的晶粒细化和延迟动态回复，增加镁含量和塑性应变在SPD。在跳跃和恒应变速率下的力学试验表明，超细晶Al-Mg合金具有复杂的变形行为：（1）锯齿状流动的临界应变ε（c）随应变和Mg含量的增加而显著增加，而粗晶和未变形的合金则相反;（二）瞬时应力响应（Δ sigma（i））和瞬时应变速率敏感性（m（i））在速率跳跃期间始终为正，并且随着CCDP道次和Mg含量而单调增加，然而，它们在应变速率跃变方向上表现出明显的不对称性，即应变速率朝下的值比应变速率朝上的值大一个数量级，并随着CCDP的进展和Mg含量的增加而增加;（3）稳态应变速率敏感性m（s）为负值，随着CCDP的进行先减小后增大。基于最近发展的DSA模型，通过将SPD过程中Al-Mg合金的微观组织演变与SPD对DSA的影响联系起来，讨论了UFG Al-Mg合金的这种力学行为。(C)2014 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
This investigation addressed the influence of severe plastic deformation (SPD) on dynamic strain aging (DSA) of ultrafine grained (UFG) Al-Mg alloys with different Mg content. Confined channel die pressing (CCDP) carried out at room temperature was used for SPD. Microcharacterization by TEM revealed a remarkable grain refinement and retarded dynamic recovery with increasing Mg content and plastic strain during SPD. Mechanical tests with jumping and constant strain rates demonstrated a complicated deformation behaviors of the UFG Al-Mg alloys: (i) the critical strain epsilon(c), for initiation of serrated flow increased considerably with increasing strain and Mg content contrary to the behavior of the coarse grained and non-deformed counterparts; (ii) the instantaneous stress response (Delta sigma(i)) and the instantaneous strain rate sensitivity (m(i)) during rate jumps were always positive and increased monotonically with CCDP pass and Mg content, however, they exhibited a distinctive asymmetry with respect to the strain rate jump direction, i.e. the values for strain rate towards down were about one order of magnitude larger than those for rate towards up and increased with progressing CCDP as well as with increasing Mg content; (iii) the steady state strain rate sensitivity m(s) was negative and decreased firstly with progressing CCDP up to a certain strain and then increased again. This mechanical behavior of UFG Al-Mg alloys is discussed on the basis of recently developed DSA models by relating the microstructure evolution of Al-Mg alloys during SPD to the influence of SPD on DSA. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.