Effect of grain size on the activation energy for plastic deformation near room temperature in a Zn–28.7 pct Al–1.9 pct Cu alloy
Effect of grain size on the activation energy for plastic deformation near room temperature in a Zn–28.7 pct Al–1.9 pct Cu alloy
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DOI：
10.1007/s10853-007-1751-2
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发表时间：
2007-06
影响因子：
4.5
通讯作者：
J. Muñoz‐Andrade;A. Mendoza-Allende;E. Cabrera;G. Torres-Villaseñor;J. Montemayor-Aldrete
中科院分区：
文献类型：
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作者：
J. Muñoz‐Andrade;A. Mendoza-Allende;E. Cabrera;G. Torres-Villaseñor;J. Montemayor-Aldrete
Zn-22wt%Al共析合金是一种超塑性材料，已被用于许多超塑性实验研究。这种合金受到了相当多的关注，因为这种材料有许多潜在的应用[1]。富锌铝合金与铁[2，3]或铜添加[2-5]，近年来一直在工程上的兴趣，因为一些合金元素的添加提高了耐磨性，弹性模量，屈服强度和耐腐蚀性的应力和温度的服务条件下，而不会有重大影响的超塑性行为在生产过程中的组件。本研究的主要目的是研究晶粒尺寸对Zn-Al-Cu合金在室温附近塑性变形激活能的影响。在这项工作中使用的合金的化学分析是Zn-28.7wt%Al-1.9wt%Cu。超塑性材料通过挤压获得，导致晶粒尺寸为2.7 μm。用这种材料制备了许多平面拉伸试样。一组试样在548 K下热处理3 h，然后在室温水中快速淬火。该处理产生0.6 μm的晶粒尺寸，通过线截距法测量[6]。使用两种粒度的试样进行实验。使用具有1.6 cm标距长度和0.2× 0.32 cm横截面的扁平拉伸试样来研究蠕变行为。蠕变试验使用恒载试验机（SATEC）进行，该试验机经过改装，可提供恒定的外加应力，所选应力的变化不超过0.7%。向样品施加1.6 MPa至20.5 MPa的应力，产生6.4* 10-9 s-1至1.6* 10-2 s-1的稳态应变速率。蠕变试验期间的应变用精确到±1.3* 10-4 cm的Schaevitz线性可变差动Transformer（LVDT）测量，并使用数据采集系统监测该信息。通过在试样保持器周围使用钨丝灯实现了从294 K到398 K的测试温度。该加热装置能够在20 s内升至试样的选定温度。试验温度恒定在±0.5 K水平。图1和图2分别示出了晶粒尺寸为2.7 μm和0.6 μm的试样的真应变e对时间t的曲线图。1和2.对2.7 μm样品的图1的检查表明，蠕变曲线显示出一个非常短的减速初级阶段，然后是稳态阶段;还显示出初级瞬态应变随施加应力的增加而增加。不像我们的实验
The Zn–22 wt pct Al eutectoid alloy is a superplastic material which has been used in a number of experimental investigations of superplasticity. Considerable attention has been devoted to this alloy, because this material has numerous potential applications [1]. Zinc-rich aluminum alloys with: Fe [2, 3] or with Copper additions [2–5], has been of engineering interest over recent years, because the addition of some alloying elements enhances the wear resistance, elastic modulus, yield strength and corrosion resistance under the service conditions of stress and temperature without having a major effect on the superplastic behavior during production of components. The main goal of this investigation is to study the effect of grain size on the activation energy for plastic deformation, near room temperature, in a Zn–Al–Cu Alloy. The chemical analysis of the alloy used in this work was Zn–28.7 wt pct Al–1.9 wt pct Cu. The superplastic material was obtained by extrusion resulting in a grain size 2.7 μm. A number of flat tensile specimens were prepared from this material. A set of specimens were heat treated at 548 K for 3h, followed by rapid quenching in water at room tempeature. This treatment produce a grain size of 0.6 μm, measured by the line intercept method [6]. The experiments were conducted using two grain size specimens. Flat tensile specimens, having 1.6 cm gage length and 0.2× 0.32 cm cross-section, were used to study creep behavior. Creep tests were carried out using a constant load machine (SATEC), which was modified to provide constant applied stress, with a variation of no more than 0.7% in the chosen stress. Stresses between 1.6 MPa and 20.5 MPa were applied to the samples producing steady state strain rates between 6.4* 10–9 s–1 to 1.6* 10–2 s–1. The strain during the creep tests was measured with a Schaevitz linear variable differential transformer (LVDT) accurate to±1.3* 10–4 cm, and this information was monitored using a data acquisition system. The test temperatures ranging from 294 K to 398 K were achieved by using tungsten lamps around the specimen holder. This heating device was capable to rise to the selected temperature of the specimen within 20 s. The test temperatures were constant at the level of±0.5 K.The plots of true strain, e, against time, t, which were obtained for specimens with grain sizes of 2.7 μm and 0.6 μm are, respectively illustrated in Figs. 1 and 2. Examination of Fig. 1 corresponding to samples with 2.7 μm has shown that the creep curves exhibit a very short decelerating primary stage followed by a steady state stage; and also exhibit that primary transient strain increases with increasing the applied stress. Unlike our experimental