Deformation-enhanced hierarchical multiscale structure heterogeneity in a Pd-Si bulk metallic glass
Deformation-enhanced hierarchical multiscale structure heterogeneity in a Pd-Si bulk metallic glass
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Pd-Si块状金属玻璃中变形增强的分级多尺度结构异质性
DOI：
10.1016/j.actamat.2020.08.077
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发表时间：
2020
期刊：
影响因子：
9.4
通讯作者：
S. Lan
中科院分区：
文献类型：
--
作者：
S.N. Liu;L.F. Wang;J.C. Ge;Z.D. Wu;Y.B. Ke;Q. Li;B.A. Sun;T. Feng;Y. Wu;J. T. Wang;H. Hahn;Y. Ren;J.D. Almer;X.-L. Wang;S. Lan
利用电子显微镜、高能同步x射线衍射和小角散射技术研究了pd82si18二元大块金属玻璃变形前后的多尺度结构。实验结果表明，变形后在多个长度尺度上，分层结构的非均质性增强。在弯曲后，观察到高数目密度的分层多剪切带，引入复杂但周期性分布的残余应变。对分布函数分析表明，中程尺度上短程簇的连通性决定了弯曲后试样中拉伸侧和压缩侧的堆积密度差。原位同步x射线衍射研究还发现，pd82si18玻璃合金在单轴拉伸和压缩下，短程团簇之间的连接模式发生了转变，这与三轴拉伸/压缩部分在弯曲时的连接模式一致。通过小角散射和透射电镜观察，形变后金属玻璃的纳米尺度非晶相分离和多剪切带相互作用可能是塑性变形增强金属玻璃纳米尺度非晶相分离的主要原因。本研究结果表明，在多长度尺度上，层次非均质结构的增强可以解释Pd-Si玻璃合金优异的塑性，加深了对金属玻璃塑性变形过程中组织-性能关系的理解。
The multiscale structures in a Pd82Si18binary bulk metallic glass before and after deformation were studied using electron microscopies, high-energy synchrotron X-ray diffraction, and small-angle scattering techniques. The experimental results revealed an enhancement of hierarchical structure heterogeneities on multiple length scales after deformation. Hierarchical multiple shear bands of high number density were observed after bending, introducing complex but periodically distributed residual strain. Pair distribution function analysis revealed that the connectivity of the short-range clusters on the medium-range scale determines the packing density difference between the tension side and the compression side in the sample after bending. In-situ synchrotron X-ray diffraction study also revealed a transformation of connection modes among short-range clusters under uniaxial tension and compression, which is consistent with those of triaxial tension/compression parts upon bending in Pd82Si18glassy alloys. The nanoscale heterogeneities for metallic glasses after deformation observed by small-angle scattering and transmission electron microscopy may be attributed to the nanoscale amorphous phase separation and interacting multiple shear bands enhanced by plastic deformation. Our findings suggested that the enhancement of hierarchical heterogeneous structure on multiple length scales may explain the excellent plasticity of Pd-Si glassy alloys, deepening the understanding of structure-property relation during plastic deformation in metallic glasses.