Microstructure and ductile-brittle transition of as-cast Zr-based bulk glass alloys under compressive testing
Microstructure and ductile-brittle transition of as-cast Zr-based bulk glass alloys under compressive testing
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DOI：
10.1016/s0921-5093(01)01260-6
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发表时间：
2001-10-15
期刊：
影响因子：
6.4
通讯作者：
Hui, XD
中科院分区：
文献类型：
--
作者：
Bian, Z;Chen, GL;Hui, XD
本文研究了不同体积分数淬火后的Zr_（52.5）Cu_（17.9）Ni_（14.6）Al_（10）Ti_5合金的力学性能和断裂机制。通过控制合金中的氧含量和浇注过程中的过热，制备了不同体积分数的淬入晶合金。通过X射线衍射、差示扫描量热仪DSC曲线和扫描电子显微镜（SEM）照片对样品的相结构、粒径和体积分数进行了表征。随着晶体体积分数从4%增加到13%，晶体的平均尺寸从0.3 μ m增加到1.3 μ m。压缩力学试验表明，随着断裂应力和塑性的显著降低，出现了韧脆转变。通过对流动变形和断口形貌的详细观察，阐明了淬入结晶与力学行为之间的关系。Zr基大块非晶合金具有典型的韧性变形和断裂行为。撕裂剪切带在断裂面上形成了典型的脉状结构。淬火晶粒对流动变形和断裂行为的影响取决于晶粒的性质、尺寸、体积分数和分布。在剪切带宽度的意义上，晶体的颗粒尺寸是关键的。当颗粒尺寸大于剪切带宽度时，由于界面分离，导致流动变形的不均匀性明显，微裂纹增多。另一方面，纳米级颗粒可以增加流动的粘度，但不会形成微裂纹，从而导致金属玻璃的颗粒强化。增大大尺寸颗粒的体积分数有利于微裂纹的泄漏和脆性断裂。随着颗粒尺寸和体积分数增加到剪切带宽度的两倍和10%体积，在压缩试验条件下，大块非晶合金的韧性断裂完全转变为脆性断裂。(C)2001 Elsevier Science B.V. Ali版权所有。
This paper investigates mechanical properties and fracture mechanisms of Zr52.5Cu17.9Ni14.6Al10Ti5 alloys with various volume fractions of quenched-in crystalline. The alloys with various volume fractions of quenched-in crystalline were prepared by controlled oxygen content of alloys and overheating of the pouring. The phase structure, particle size and volume fraction of all samples were identified by X-ray diffraction, differential scanning calorimeter DSC curves and scanning electron microscopy (SEM) photographs. The mean sizes of crystalline increased from 0.3 to 1.3 mum with increasing volume fraction of crystalline from 4 to 13%. The compressive mechanical tests show a ductile-brittle transition with significant decrease in the fracture stress and ductility. Detailed observations in the flow deformation and fracture surface illustrate the relationship between the quenching-in crystalline and the mechanical behavior. The full bulk amorphous Zr-based alloy exhibits typical ductile deformation and fracture behavior. The torn shear bands form the typical vein patterns on the fracture surface. The effects of quenching-in crystalline on the flow deformation and fracture behavior depend on the nature, size, volume fraction and distribution. The particle size of the crystalline in the sense of the width of shear bands is critical. When the size is larger than the width of the shear bands the particles induce an obvious inhomogeneity of the flow deformation and more microcracks by the separation of the interfaces. Nano-scale particles, on the other hand, may increase the viscosity of the flow but do not form microcracks, resulting in particle strengthening of the metallic glass. Increasing the volume fraction of large-scale particles is favorable to leaking the microcracks and brittle fracture. With increasing particle size and volume fraction up to two times the width of the shear band and 10% vol., respectively, the ductile fracture of bulk amorphous alloy completely transforms to brittle fracture under compressive testing. (C) 2001 Elsevier Science B.V. Ali rights reserved.