Time-dependent deformation mechanism of metallic glass in different structural states at different temperatures
Time-dependent deformation mechanism of metallic glass in different structural states at different temperatures
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DOI：
10.1016/j.jnoncrysol.2021.121221
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发表时间：
2021-11-10
影响因子：
3.5
通讯作者：
Mukherjee, Sundeep
中科院分区：
文献类型：
--
作者：
Ghodki, Nandita;Sadeghilaridjani, Maryam;Mukherjee, Sundeep
人们对非晶合金随时间的塑性变形行为作为其结构状态的函数的理解有限。本文采用纳米压痕技术研究了Zr52.5Ti5Cu17.9Ni14.6Al10大块金属玻璃在铸态和松弛状态下的蠕变行为，施加的载荷范围为500 ~ 1500 mN，温度范围为室温~ 573 K。蠕变位移随载荷和温度的升高而增大，这是由于高温和高载荷下蠕变过程是热激活的，扩散速率加快。蠕变应变率敏感性随温度的升高和外加载荷的减小而增大，是衡量蠕变机理的指标。这归因于从局部蠕变到更均匀蠕变的转变。与铸态合金相比，松弛合金的自由体积减小导致蠕变位移降低，应变率敏感性提高。结果表明，在高温下，以扩散为基础的变形占主导地位，而在室温下，以剪切转变为媒介的塑性占主导地位。利用协同剪切模型计算了金属玻璃的剪切转变区体积，并将其与结构状态相关联，从而深入了解温度和载荷作用下的变形过程。
There is limited understanding of time-dependent plastic deformation behavior of amorphous alloys as a function of their structural state. Here, the creep behavior of Zr52.5Ti5Cu17.9Ni14.6Al10 bulk metallic glass was investigated in its as-cast and relaxed states using nanoindentation technique with applied load in the range of 500-1500 mN and temperature in the range of room temperature to 573 K. The creep displacement increased with increasing load and temperature since the creep process is thermally activated and diffusion rate is enhanced at elevated temperature and higher load. The creep strain rate sensitivity, which is a measure of the creep mechanism, increased with increase in temperature and decrease in applied load. This was attributed to the transition from localized to more homogeneous creep. Reduction in free volume for the relaxed alloy resulted in lower creep displacement and larger strain rate sensitivity compared to its as-cast counterpart. The results suggest that diffusion-based deformation dominate at higher temperature in contrast to shear transformation mediated plasticity at room temperature. The volume of shear transformation zone for the metallic glass was calculated using cooperative shearing model and correlated with the structural state for fundamental insights into the deformation process as a function of temperature and load.