The effects of elastic cycling in nanoindentation of a metallic glass
The effects of elastic cycling in nanoindentation of a metallic glass
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DOI：
10.1080/14786435.2020.1814494
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发表时间：
2020-09
影响因子：
1.6
通讯作者：
C. M. Meylan;A. Greer
中科院分区：
文献类型：
--
作者：
C. M. Meylan;A. Greer
摘要利用纳米压痕技术对块体金属玻璃Cu46Zr46Al7Gd1进行弹性循环，并对其进行表征。根据多条加载曲线，确定了几种性能的累积分布，包括初始屈服载荷、硬度和压痕模数。这些分布以中位数属性值和宽度为特征。比较了压头尖端弹性循环与退火热循环和低温热循环对大块玻璃的影响。我们证实，弹性循环显著增加了初始屈服载荷，并找到了局部强化的证据。在关于这种明显强化的最初报告中，它被归因于刺激玻璃的松弛到更有序的结构，这种效果将类似于退火。相反，我们得出的结论是，屈服载荷的增加不是由于玻璃中的结构有序化，而是由于滞弹性应变引起的压缩残余应力。虽然弹性循环可能会对金属玻璃的结构产生影响，但这些影响并不能通过纳米压痕中的加载来揭示。
ABSTRACT We use nanoindentation to perform elastic cycling on, and to characterise, the bulk metallic glass Cu46Zr46Al7Gd1. From multiple loading curves, cumulative distributions are determined for several properties, including the initial yield load, the hardness and the indentation modulus. The distributions are characterised by the median property value and by their width. The effects of elastic cycling under the indenter tip are compared with those of annealing and of cryogenic thermal cycling applied to the bulk glass. We confirm that elastic cycling significantly increases the initial yield load, and find evidence for localised strengthening. In the first reports of this apparent strengthening, it was attributed to stimulation of relaxation of the glass to a more ordered structure, an effect that would be similar to that of annealing. In contrast, we conclude that the increased yield load is not due to structural ordering in the glass, but to compressive residual stress resulting from anelastic strains. While there may be effects of elastic cycling on the structure of metallic glasses, these are not revealed by loading in nanoindentation.