Strain rate-dependent deformation in bulk metallic glasses
Strain rate-dependent deformation in bulk metallic glasses
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DOI：
10.1016/s0966-9795(02)00146-2
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发表时间：
2002-11-01
期刊：
影响因子：
4.4
通讯作者：
Li, Y
中科院分区：
文献类型：
--
作者：
Nieh, TG;Schuh, C;Li, Y
金属玻璃具有亚稳态结构。因此，它们的塑性变形取决于结构动力学。在本文中，我们提出了从Zr基和La基金属玻璃获得的数据，并讨论了塑性变形的动力学方面，包括均匀和非均匀变形。在均匀变形（通常发生在过冷液体区域）的情况下，牛顿行为并不是普遍观察到的，通常只发生在低应变速率下。在高应变速率下，通常观察到非牛顿行为。它表明，这种非牛顿行为与原位结晶的非晶结构。在非均匀变形（发生在室温下）的情况下，变形由局部剪切带控制。同时，利用纳米压痕仪在较宽的应变速率范围内对镧基金属玻璃的塑性变形进行了研究。在低速率下，压痕过程中的载荷-位移曲线表现出许多锯齿或弹出，但随着压痕速率的增加，这些锯齿变得不那么突出。使用的尖端速度在弹出作为衡量锯齿活动，我们发现，锯齿状流是唯一显着的压痕应变率低于一定的临界值。(C)2002爱思唯尔科技有限公司。保留所有权利。
Metallic glasses have metastable structures. As a result, their plastic deformation is dependent upon structural dynamics. In the present paper, we present data obtained from Zr-base and La-base metallic glasses and discuss the kinetic aspects of plastic deformation, including both homogeneous and heterogeneous deformation. In the case of homogeneous deformation (typically occurring in the supercooled liquid region), Newtonian behavior is not universally observed and usually takes place only at low strain rates. At high strain rates, non-Newtonian behavior is usually observed. It is demonstrated that this non-Newtonian behavior is associated with in situ crystallization of the amorphous structure. In the case of heterogeneous deformation (occurring at room temperature), deformation is controlled by localized shear banding. The plastic deformation of a La-base metallic glass is also investigated using instrumented nanoindentation experiments over a broad range of indentation strain rates. At low rates, the load-displacement curves during indentation exhibit numerous serrations or pop-ins, but these serrations become less prominent as the indentation rate is increased. Using the tip velocity during pop-in as a gauge of serration activity, we find that serrated flow is only significant at indentation strain rates below a certain critical value. (C) 2002 Elsevier Science Ltd. All rights reserved.