The effect of Al2Cu precipitates on the microstructural evolution, tensile strength, ductility and work-hardening behaviour of a Al-4 wt.% Cu alloy processed by equal-channel angular pressing
The effect of Al2Cu precipitates on the microstructural evolution, tensile strength, ductility and work-hardening behaviour of a Al-4 wt.% Cu alloy processed by equal-channel angular pressing
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DOI：
10.1016/j.actamat.2012.09.038
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发表时间：
2013-01-01
期刊：
影响因子：
9.4
通讯作者：
Ferrante, Maurizio
中科院分区：
文献类型：
--
作者：
Prados, Erika F.;Sordi, Vitor L.;Ferrante, Maurizio
金属和合金的抗拉强度可以通过剧烈的塑性变形大大提高，这是极端晶粒细化的结果。然而，延展性通常会降低，因此已经实施了一些策略来尽量减少这一缺点。本文研究了等径角压（ECAP）处理的铸态均匀al- 4wt .% Cu合金中析出物的影响。研究了两种初始条件：(1)均质后快速冷却得到的固溶体；（ii）从均质温度缓慢冷却得到的粗Al2Cu析出物。经ECAP处理后，在100℃和170℃下进行热处理，al - α晶粒尺寸减小到200-300 nm，抗拉强度大幅提高。对于加工硬化能力，采用Kocks-Mecking图对应力-应变数据进行重新解释。设计了不同的析出相分散体，其对加工硬化速率的影响与这些分散体的定量金相参数有关。因此，观察到非常细的Al2Cu分散的有利影响，这种行为归因于沉淀的位错钉住，其主要影响是动态回复率的降低。这一战略的实施将产生积极的技术效果，因为除了强度的提高之外，均匀伸长率和加工硬化能力之间也有明确的相关性。(C) 2012材料学报Elsevier Ltd.出版。版权所有。
The tensile strength of metals and alloys can be considerably increased by severe plastic deformation, a consequence of the extreme grain refinement thus achieved. However, ductility is generally reduced and therefore a number of strategies have been implemented to minimize this drawback. The present paper examines the effect of precipitation on a cast and homogenized Al-4 wt.% Cu alloy processed by equal-channel angular pressing (ECAP). Two initial conditions were studied: (i) solid solution obtained by fast cooling after homogenization; and (ii) coarse Al2Cu precipitates obtained by a very slow cooling from the homogenization temperature. After ECAP processing these groups were submitted to heat treatments performed at 100 and 170 degrees C. The Al-alpha grain size was reduced to 200-300 nm and the tensile strength was substantially increased. As for the work-hardening capacity, reinterpretation of the stress-strain data was carried out in terms of Kocks-Mecking plots. The experimental work was devised so as to produce different precipitate dispersions, whose effect on the work-hardening rate was correlated with the quantitative metallographic parameters of such dispersions. The beneficial effect of a very fine Al2Cu dispersion was thus observed, and this behaviour was attributed to dislocation pinning by the precipitates, an occurrence whose main effect is a decrease in the dynamic recovery rate. Implementation of this strategy will have positive technological effects since, besides the improvement in strength, a definite correlation between uniform elongation and work-hardening capacity was clearly demonstrated. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.