Using spherical indentation to measure the strength of copper-chromium-zirconium
Using spherical indentation to measure the strength of copper-chromium-zirconium
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DOI：
10.1016/j.jnucmat.2018.04.012
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发表时间：
2018-12
影响因子：
3.1
通讯作者：
A. Cackett;J. Lim;Przemysław Klupś;A. Bushby;C. Hardie
中科院分区：
文献类型：
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作者：
A. Cackett;J. Lim;Przemysław Klupś;A. Bushby;C. Hardie
沉淀硬化CuCrZr将用于ITER托科马克的热沉组件，并且是EU DEMO的主要候选材料。由于涉及放射性物质和所需的相对较大的样品尺寸的挑战，使用传统的标准化技术测量辐照CuCrZr的机械性能是困难的。球形纳米压痕提供了一种技术，可以用比传统测试小得多的体积测量应力-应变特性。在这项工作中，CuCrZr在不同的温度下进行热处理，以改变Cr析出物的大小和间距。然后采用多尖端半径的球形纳米压痕法对所有样品进行应力应变曲线的绘制，并由此计算初始流变应力值。结果表明，在形成塑性所需的应力中存在较强的压痕尺寸效应（ISE），但在较高的压痕应变下，随着尖端半径R≥8 μm，流动应力趋于恒定。这表明，在塑性变形开始时，ISE主要由位错源激活，但在后期阶段，与微结构材料长度尺度的相互作用主导了测量的机械强度。这些小规模试验的力学响应受多种机制的支配，这使数据的解释变得复杂，在测量辐照对力学性能的影响时必须加以考虑。
Precipitation hardened CuCrZr will be used in heat-sink components in the ITER tokomak and is a primary candidate for EU DEMO. The measurement of mechanical properties of irradiated CuCrZr using conventional, standardised techniques is difficult due to the challenges involved in working with radioactive material and the relatively large specimen size required. Spherical nano-indentation offers a technique to measure stress-strain properties from far smaller volumes than conventional tests. In this work, CuCrZr has been heat-treated at different temperatures to vary the Cr precipitate size and spacing. Spherical nano-indentation using multiple tip radii was then used to produce stress-strain curves for all samples, from which values of initial flow stress were calculated. It was found that there was a strong indentation size effect (ISE) in the stress required to initiate plasticity, however at higher indentation strains the flow stress became constant for tip radii, R, ≥8 μm. This suggests that at the initiation of plastic deformation the ISE is dominated by dislocation source activation but in later stages the interaction with microstructural material length-scales dominate the measured mechanical strength. The mechanical response of these small-scale tests is governed by multiple mechanisms, which convolute interpretation of data and must be considered when measuring the effects of irradiation on the mechanical properties.