Deformation and fracture of Zr51Ti5Ni10Cu25Al9 bulk metallic glass under rapid heating and pre-load
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摘要: 实验研究了不同预压载荷与加热速率下Zr51Ti5Ni10Cu25Al9块体非晶合金的失效温度和破坏规律, 发现预压力和温升率较低时, 随着温度的升高, 材料强度减小, 样品最后发生塑性变形; 预压力和温升率较高时样品则发生剪切断裂, 且发生剪切破坏时样品的温度高于其玻璃化转变温度.基于变温条件下的结构弛豫模型, 分析了块体非晶合金在快速加热条件下的变形过程,给出了材料发生屈服时的温度与温升率、预压力与屈服温度之间的相互关系, 并得出了实验结果的拟合关系式. 对回收样品断裂面进行分析, 发现了与恒温压缩断裂明显不同的断裂特征. 最后分析了预压载荷下快速加热过程中上述材料发生剪切破坏的临界条件.Abstract: Bulk metallic glasses are regarded as potentialengineering materials because of their unique mechnical and physicalproperties. Mechanical behavior of bulk metallic glass and its compositeover a wide range of strain rates and temperatures attracted manyresearchers' interests. In this paper, a systematic experimental study wereperformed on Gleeble3500 thermal-mechanical testing system to study theeffects of heating rates on mechanical behavior ofZr51Ti5Ni10Cu25Al9 bulk metallic glass underpre-load. The results show that failure models of this material changes fromheating soften to catastrophic rupture with increasing pre-load and heatingrate. Under low pre-load, yield behavior ofZr51Ti5Ni10Cu25Al9 bulk metallic glass iscontrolled by both pre-stress and heating rate; under high pre-load andheating rate the material failures in shear fracture mode and thetemperature of destructive sample is close to or above the glass transitiontemperature when catastrophic rupture occurs, meanwhile the pre-stress ismuch lower than the strength at room temperature and characters of therupture surface are unusual with quasi-static compression experimentalresults. Structure relaxation of amorphous alloy under changing temperatureis discussed and the relations of yield temperature and heating rate as wellas pre-stress are deduced. The reason of catastrophic rupture under thisexperimental condition is also analyzed based on metallographic observationof recovery samples and a critical failure model is also given out.
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Key words:
- bulk metallic glass /
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