Cavity growth during superplastic flow in an Al-Mg alloy: I. Experimental study
Cavity growth during superplastic flow in an Al-Mg alloy: I. Experimental study
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DOI：
10.1016/s1359-6454(01)00399-8
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发表时间：
2002-03-14
期刊：
影响因子：
9.4
通讯作者：
Ghosh, AK
中科院分区：
文献类型：
--
作者：
Bae, DH;Ghosh, AK
定量评价了细晶Al-Mg-Mn-Cu合金单轴拉伸时超塑性应变引起的空化。拉伸试验是在450摄氏度到550摄氏度的恒定温度下，在10(-4)S(-1)到10(-2)S(-1)的范围内进行的。在这些试验中，由于应变率和温度历史确实影响空化的程度，因此要注意达到应变率控制的精确度。通过对光学显微镜下观察并由扫描电子显微镜支持的测试样品进行图像分析，测量了空洞的数量和大小。随着应变的增加，空洞人口密度增加，这是以前看到的结果，但没有详细研究。还仔细监测了空洞的生长，发现这是由于空洞周围基质的塑性变形造成的。孔洞的总体积分数是上述两个组分的乘积，随着应变的增加呈指数增加。然而，空腔体积分数与应变率和温度的依赖关系并不是直接的。根据实验上观察到的基质与不可变形颗粒之间的脱粘、新空洞的持续形核以及空洞塑性长大的相关数据，试图解释这些复杂的效应。(C)2002年，由爱思唯尔科学有限公司代表Acta Materialia Inc.出版。
Cavitation caused by superplastic straining of a fine-grained Al-Mg-Mn-Cu alloy under uniaxial tension has beets quantitatively evaluated. Tensile tests were conducted at constant true strain rate in a range of 10(-4)s(-1) to 10(-2)s(-1) at constant temperatures between 450 C and 550 degreesC. Care was exercised to achieve precision in strain-rate control in these tests since strain-rate and temperature history do affect the extent of cavitation. Measurements of the number and size of cavities were made by using image analysis on tested specimens viewed by optical microscopy and further supported by SEM. With increasing strain, the cavity population density increases, a result seen previously but not studied in detail. Cavity growth was also monitored carefully and found to be due to the plastic deformation of the matrix surrounding the cavity. The total volume fraction of cavities which is the product of the above two components was found to increase exponentially with strain. The dependencies of cavity volume fraction on strain-rate and temperature are not straightforward, however. Based on experimental observations of decohesion between matrix and non-deformable particles, continuous nucleation of new cavities, and data related to plasticity-based growth of cavities, attempts are made to explain these complex effects. (C) 2002 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.