Composition dependence of metallic glass plasticity and its prediction from anelastic relaxation – A shear transformation zone analysis
Composition dependence of metallic glass plasticity and its prediction from anelastic relaxation – A shear transformation zone analysis
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DOI：
10.1016/j.actamat.2020.04.053
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发表时间：
2020-08
期刊：
影响因子：
9.4
通讯作者：
T. Lei;L. DaCosta;M. Liu;Jie Shen;Y. H. Sun;Wen-chao Wang;Michael Atzmon
中科院分区：
文献类型：
--
作者：
T. Lei;L. DaCosta;M. Liu;Jie Shen;Y. H. Sun;Wen-chao Wang;Michael Atzmon
金属玻璃的力学弛豫行为具有成分敏感性。例如，在动态力学分析中，La 70 Ni 15 Al 15在高频和/或低温下显示出归一化损耗模量的明显的第二峰，称为β弛豫，而La 70 Cu 15 Al 15仅显示出肩部。我们已经确定了这些合金在室温下的弛豫时间谱超过11个数量级的时间从准静态滞弹性弛豫测量。这些都是用来表征剪切转变区（STZ）在α和β制度的属性。La_（70）Ni_（15）Al_（15）样品中的β弛豫峰明显，这是由于快、小电位STZ的体积分数较大，慢、大电位STZ的体积分数较小所致。室温拉伸试验表明，随着应变速率的降低，塑性增加，这是热激活过程的特征。La 70 Cu 15 Al 15比La 70 Ni 15 Al 15表现出更大的塑性，与β弛豫强度呈负相关，这与之前提出的相反。STZ谱被用来解释两种合金之间的塑性差异。从损耗模量测量的塑性预测需要修订，并需要绝对测量。
The mechanical relaxation behavior of metallic glasses (MGs) is composition sensitive. For example, in dynamic mechanical analysis, La70Ni15Al15shows a pronounced secondary peak, termed β relaxation, of the normalized loss modulus at high frequency and/or low temperature, while La70Cu15Al15only exhibits a shoulder. We have determined relaxation-time spectra at room temperature for these alloys over eleven orders of magnitude of time from quasi-static anelastic relaxation measurements. These are employed to characterize shear transformation zone (STZ) properties in both the α and β regimes. The pronounced β relaxation peak, observed for La70Ni15Al15, is a result ofbothlarger volume fraction of fast and smallpotentialSTZsandsmaller volume fraction of slow and largepotentialSTZs as compared to La70Cu15Al15. Room-temperature tensile tests show increasing plasticity with decreasing strain rates, characteristic of thermally activated processes. La70Cu15Al15exhibits greater plasticity than La70Ni15Al15, a negative correlation with the intensity of the β relaxation that is opposite to that previously suggested. The STZ spectra are used to explain the plasticity difference between the two alloys. Plasticity predictions from loss modulus measurements need to be revised, and require absolute measurements.