Stored energy, vacancies and thermal stability of ultra-fine grained copper
Stored energy, vacancies and thermal stability of ultra-fine grained copper
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DOI：
10.1016/j.msea.2008.02.048
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发表时间：
2008-09-25
期刊：
影响因子：
6.4
通讯作者：
Daviesa, C. H. J.
中科院分区：
文献类型：
--
作者：
Cao, W. Q.;Gu, C. F.;Daviesa, C. H. J.
采用差示扫描量热法研究了室温下等通道转角挤压16道次的无氧铜的储能和热稳定性。储存能量随着应变增加至四次通过，之后其在0.95 +/-0.05J/g处饱和。该饱和值比传统冷轧高20%。经过八道次后的铜的显微组织的特征在于约0.21 μ m的平均亚晶粒尺寸和约35%的高角度边界分数。计算并比较了缺陷对储能的贡献，表明储能主要来源于晶界和空位。8次循环后的恢复活化能为77 ~ 80 kJ/mol。与冷轧铜相比，较高的储能和较低的激活能归因于过量的空位。(C)2008 Elsevier B. V.保留所有权利。
The stored energy and thermal stability of oxygen-free high conductivity copper processed by equal channel angular pressing up to 16 passes at room temperature was studied by differential scanning calorimetry. Stored energy increased with strain up to four passes, after which it saturated at 0.95 +/- 0.05 J/g. This saturation value is 20% higher than from conventional cold rolling. The microstructure of the copper after eight passes was characterized by an average subgrain size of about 0.21 mu m and high-angle boundary fraction of about 35%. The contributions to the stored energy from defects were calculated and compared, suggesting that the stored energy mainly originates from boundaries and vacancies. The restoration activation energy after eight passes was between 77 and 80 kJ/mol. The higher stored energy and lower activation energy compared to cold-rolled copper is attributed to excess vacancies. (C) 2008 Elsevier B.V. All rights reserved.