Characterization of Shear Banding in La-Based Bulk Metallic Glasses through Indentation
Characterization of Shear Banding in La-Based Bulk Metallic Glasses through Indentation
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DOI：
10.2320/matertrans.mj200761
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发表时间：
2007-07
影响因子：
1.2
通讯作者：
W. Peng;B. Wei;Taihua Zhang;Yuan-yuan Liu;Lei Li
中科院分区：
文献类型：
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作者：
W. Peng;B. Wei;Taihua Zhang;Yuan-yuan Liu;Lei Li
采用铜模铸造法制备了La 64Al 14（Cu，Ni）（22）、La（63.1）Al（5.2）（Cu，Ni）（21.7）、La 57.6Al 17.5（Cu，Ni）（24.9）和La 55Al 25Cu 10Ni 5Co 5低玻璃化转变温度块体非晶合金。四种BMG的同源温度（室温与Tg的比值）范围为0.64至0.73。采用纳米压痕法研究了不同加载速率下BMG的塑性变形行为。结果表明，锯齿流的加载速率依赖性强烈依赖于同系温度，而锯齿流与剪切带的形核和扩展有关。具有相对高的同系温度的合金表现出随着加载速率的增加而增加的流动锯齿。而具有低同系温度的合金在低速率下表现出显著的锯齿。在所有加载速率下，纳米压痕后，所有合金的压痕周围都没有观察到明显的剪切带。或者，剪切带图案通过宏观压痕来表征。结果表明，剪切带间距随同系温度的升高而减小。
La64Al14(Cu,Ni)(22), La(63.1)All(5.2)(Cu,Ni)(21.7), La57.6Al17.5(Cu,Ni)(24.9), and La55Al25Cu10Ni5Co5 bulk metallic glasses (BMGs) with low glass transition temperature (T-g) were prepared by copper-mould casting method. The homologous temperature (the ratio of room temperature to T-g) of the four BMGs ranges from 0.64 to 0.73. Plastic deformation behavior of the BMGs at various loading rates was studied by nanoindentation. The results showed that the loading rate dependency of serrated flow, which is related to the nucleation and propagation of shear bands, depends strongly on the homologous temperature. The alloys with relatively high homologous temperature exhibit an increase in flow serration with increasing loading rate. whereas. the alloys with low homologous temperature exhibit prominent serrations at low rates. No distinct shear band is observed around the indents for all alloys after nanoindentation at all the studied loading rates. Alternately, shear band pattern are characterized through macro-indentation. which shows that shear band spacing decreases with the increase of the homologous temperature.