Slip statistics for a bulk metallic glass composite reflect its ductility
Slip statistics for a bulk metallic glass composite reflect its ductility
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DOI：
10.1063/1.5051723
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发表时间：
2018-11
影响因子：
3.2
通讯作者：
W. Wright;Alan A. Long;X. Gu;Xin Liu;T. Hufnagel;K. Dahmen
中科院分区：
文献类型：
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作者：
W. Wright;Alan A. Long;X. Gu;Xin Liu;T. Hufnagel;K. Dahmen
以极高的时间分辨率和极低的噪声测量了含有微晶析出物的大块非晶复合材料的应力-时间曲线上的锯齿。对于不含微晶但也进行了单轴压缩测试的脆性金属玻璃，也进行了类似的测量。尽管两种材料的结构和应力-应变行为有显著差异，但锯齿的统计数据遵循一个简单的平均场模型，该模型将塑性变形描述为滑移薄弱点的雪崩引起的塑性变形。结晶析出物的存在减少了大滑移的数量，相对于应力-时间数据中记录的小滑移的数量，与模型预测一致。结果与平均场预测一致，即复合材料的衰减参数比整体金属玻璃的小；该衰减参数解释了两者之间潜在的微观结构差异。以极高的时间分辨率和低噪声测量了含有微晶析出物的大块金属玻璃复合材料的应力-时间曲线上的锯齿。对于不含微晶但也进行了单轴压缩测试的脆性金属玻璃，也进行了类似的测量。尽管两种材料的结构和应力-应变行为有显著差异，但锯齿的统计数据遵循一个简单的平均场模型，该模型将塑性变形描述为滑移薄弱点的雪崩引起的塑性变形。结晶析出物的存在减少了大滑移的数量，相对于应力-时间数据中记录的小滑移的数量，与模型预测一致。结果与平均场预测的结果一致，即复合材料的弱化参数比整体金属玻璃的弱化参数小；弱化参数解释了两者之间潜在的微观结构差异。
Serrations in the stress-time curve for a bulk metallic glass composite with microscale crystalline precipitates were measured with exceptionally high temporal resolution and low noise. Similar measurements were made for a more brittle metallic glass that did not contain crystallites but that was also tested in uniaxial compression. Despite significant differences in the structure and stress-strain behavior, the statistics of the serrations for both materials follow a simple mean-field model that describes plastic deformation as arising from avalanches of slipping weak spots. The presence of the crystalline precipitates reduces the number of large slips relative to the number of small slips as recorded in the stress-time data, consistent with the model predictions. The results agree with mean-field predictions for a smaller weakening parameter for the composite than for the monolithic metallic glass; the weakening parameter accounts for the underlying microstructural differences between the two.Serrations in the stress-time curve for a bulk metallic glass composite with microscale crystalline precipitates were measured with exceptionally high temporal resolution and low noise. Similar measurements were made for a more brittle metallic glass that did not contain crystallites but that was also tested in uniaxial compression. Despite significant differences in the structure and stress-strain behavior, the statistics of the serrations for both materials follow a simple mean-field model that describes plastic deformation as arising from avalanches of slipping weak spots. The presence of the crystalline precipitates reduces the number of large slips relative to the number of small slips as recorded in the stress-time data, consistent with the model predictions. The results agree with mean-field predictions for a smaller weakening parameter for the composite than for the monolithic metallic glass; the weakening parameter accounts for the underlying microstructural differences between the two.