Enhanced formability of a Zr-based bulk metallic glass in a supercooled liquid state by vibrational loading
Enhanced formability of a Zr-based bulk metallic glass in a supercooled liquid state by vibrational loading
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通过振动加载增强过冷液态锆基大块金属玻璃的成型性
DOI：
10.1016/j.actamat.2013.11.009
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发表时间：
2014-02-15
期刊：
影响因子：
9.4
通讯作者：
Liu, Lin
中科院分区：
文献类型：
--
作者：
Li, Ning;Xu, Xiaona;Liu, Lin
提出了一种提高块体金属玻璃过冷液态热塑性成形性能的新方法--振动加载。作为表征成形性的指标，拉应变随着加载频率的增加而增加，表明振动加载有利于成形性。在理论分析和有限元模拟的基础上，对该现象的物理机制进行了合理的解释。理论分析表明，在相对较高的加载频率下，试件中流动单元的分布更加均匀，具有较小的体积和较大的自由体积浓度。结合自由体积本构关系的有限元模拟结果表明，随着加载频率的增加，自由体积浓度增大，与理论分析一致。最后，进行了振动载荷下的压缩和热压试验，进一步验证了该技术的适用性。这些结果不仅为大块金属玻璃的热塑性成形，特别是微/纳米尺度的成形提供了一种有效的方法，而且可以更好地理解振动载荷下金属过冷液的结构演化。皇冠版权(C)2013由爱思唯尔有限公司代表Acta Materialia Inc.出版。保留所有权利。
Vibrational loading was introduced as an innovative method to improve the thermoplastic formability of Zr35Ti30Be26.75Cu8.25 bulk metallic glass in a supercooled liquid state. The tensile strain, as a measure to characterize the formability, increased with increasing loading frequency, indicating a vibrational loading facilitated formability. The physical mechanism of this phenomenon was rationalized on the basis of both theoretical analysis and finite-element-method simulation. The theoretical analysis revealed that a more homogeneous distribution of flowing units with a smaller volume, together with a larger free volume concentration, existed in the specimen under relatively higher loading frequencies. The finite-element-method simulation combined with the free volume constitutive relation exhibited an increase in free volume concentration with increasing loading frequency, in agreement with theoretical analysis. Finally, compressive and hot-embossing tests under vibrational loading were carried out to further verify the applicability of this technique. The present results not only provide an effective method to facilitate the thermoplastic formability of bulk metallic glasses, especially in micro/nanoscale forming, but also offer a better understanding of the structural evolution of the metallic supercooled liquid under vibrational loading. Crown Copyright (C) 2013 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.