Deformation Mechanisms in Nanocrystalline Nickel at Low Temperatures
Deformation Mechanisms in Nanocrystalline Nickel at Low Temperatures
复制标题
纳米晶镍低温变形机制
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
W. Skrotzki
中科院分区：
文献类型：
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作者：
L. Hollang;K. Reuther;S. Dey;E. Hieckmann;W. Skrotzki
本文的目的是量化和可视化金属多晶体中由晶粒度引起的变形机制的转变，从大晶粒度的传统位错-位错相互作用到(可能)“纳米”区域的位错-晶界相互作用。由于这两种类型的相互作用都是热激活的，热激活分析可以用来区分它们。为此，在4~320K温度范围内，对晶粒度为140 nm的纯脉冲电沉积镍进行了动态拉伸实验和应力松弛实验。结果表明，转变温度在77K左右。一个意想不到的结果是，变形机制存在第二次转变，只有在很低的温度下才能观察到，即从传统的位错-位错相互作用控制的均匀变形模式向“灾变剪切”局域变形模式转变。
It is the aim of the present paper to quantify and visualise the grain size induced transition of the deformation mechanism in metal polycrystals from the conventional dislocation–dislocation interaction at large grain sizes to (probably) dislocation–grain boundary interaction in the “nano” region. Since both types of interaction are thermally activated, thermal activation analysis can be used to discriminate between them. For this purpose dynamic tensile tests with stress relaxation tests were performed on pure pulsed electrodeposited nickel with 140 nm grain size at temperatures between 4 and 320 K. The results clearly indicate the transition temperature to be around 77 K. A rather unexpected result is the existence of a second transition of the deformation mechanism, which is only observable at very low temperatures namely from the homogeneous deformation mode governed by conventional dislocation–dislocation interaction towards localized deformation by “catastrophic shear”.