CREEP AND DUCTILITY IN AN AL-CU SOLID-SOLUTION ALLOY
CREEP AND DUCTILITY IN AN AL-CU SOLID-SOLUTION ALLOY
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DOI：
10.1007/bf02647082
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发表时间：
1987-12-01
期刊：
影响因子：
--
通讯作者：
MOHAMED, FA
中科院分区：
文献类型：
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作者：
CHAUDHURY, PK;MOHAMED, FA
在773~853K温度范围内，在10-5~7×10-4的归一化剪应力范围内，研究了Al-3wtPct铜合金的高温蠕变行为。结果表明，存在三个不同的区域。在I区(低应力)，应力指数为4.5，激活能为155kJ/mole。在中间应力区域II，应力指数为3.2，激活能为151kJ/mole。在高应力区，应力指数为4.5，激活能为205kJ/mole。三个区的蠕变曲线均为正常的初生期，但第II区的蠕变程度不如第I区和第III区明显。第I区和第II区的蠕变特征以及两区之间的转变应力值符合固溶体合金变形准则的预测。虽然III区(高应力)的出现与位错脱离溶质原子气氛有很好的相关性，但该区域的蠕变特征与现有的任何高应力蠕变机制都不完全一致。853K时的延伸率-断口-初始应变速率曲线在应变速率为1×10-4和6×10-4s-1时出现两个峰值。第一个峰(1×10-4s-1)是合金蠕变应力指数随应变率变化的结果，第二个峰(6×10-4s-1)反映了溶质阻力对位错速度的影响。
High-temperature creep was investigated in an Al-3 wt pct Cu alloy at temperatures in the range of 773 to 853 K and at a normalized shear stress range extending from 10-5to 7 × 10-4. The results show the presence of three distinct regions. In region I (low stresses), the stress exponent is 4.5 and the activation energy is 155 kJ/mole. In region II (intermediate stresses), the stress exponent is 3.2 and the activation energy is 151 kJ/mole. In region III (high stresses), the stress exponent is 4.5 and the activation energy is 205 kJ/mole. Creep curves obtained in the three regions exhibit a normal primary stage, but the extent of the stage is less pronounced in region II than in regions I and III. The creep characteristics in regions I and II, along with the values of the transition stresses between the two regions, are in conformity with the prediction of the deformation criterion for solid-solution alloys. While the advent of region III (high stresses) correlates well with dislocation breakaway from a solute-atom atmosphere, the creep characteristics in this region are not entirely consistent with any of the existing high-stress creep mechanisms. The plot of elongation to fracturevsinitial strain rate at 853 K exhibits two peaks at strain rates of 1 × 10-4and 6 × 10-4s-1. The first peak (1 × 10-4s-1) is attributed to the variation of the stress exponent for creep in the alloy with strain rate, and the second peak (6 × 10-4s-1) appears to reflect the effect of solute drag on dislocation velocity.