Fatigue endurance limit and crack growth behavior of a high-toughness Zr61Ti2Cu25Al12 bulk metallic glass
Fatigue endurance limit and crack growth behavior of a high-toughness Zr61Ti2Cu25Al12 bulk metallic glass
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高韧性Zr61Ti2Cu25Al12大块金属玻璃的疲劳极限和裂纹扩展行为
DOI：
10.1016/j.actamat.2015.07.071
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发表时间：
2015-10-15
期刊：
影响因子：
9.4
通讯作者：
Xu, Jian
中科院分区：
文献类型：
--
作者：
Song, Zhen-Qiang;He, Qiang;Xu, Jian
报道了一种具有高断裂韧性的大块非晶(ZT1)的疲劳损伤行为。ZT1的疲劳极限是所有BMG中最高的，归一化疲劳极限为Sigma(A)=440 Mpa(在加载比为0.1的四点弯曲中)，或类似于其拉伸强度的0.27。应力/寿命试验中的裂纹扩展阻力来自于大量剪切带导致的裂尖塑性屏蔽，以及遵循“之”字形的偏转裂纹路径。确定了应力强度因子(Delta K)的范围与裂纹扩展速率(每循环裂纹扩展数da/dN)之间的关系。ZT1的疲劳阈值为2.8 Mpa的根m，这似乎与剪切带形核的开始有关。疲劳裂纹扩展有三种不同的模式，da/dN-Delta K曲线的斜率不同，这归因于不同的微观机制。在巴黎区，断裂表面的每个疲劳条纹是由多个加载循环产生的，而不是由一个加载循环产生的。一般而言，BMG的增量K-th与其断裂韧性大致成比例。在不同的K值下，剪切带似乎扮演着不同的角色，或促进或钝化裂纹的扩展。(C)2015 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
We report the fatigue damage behavior of a Zr61Ti2Cu25Al12 (ZT1) bulk metallic glass (BMG), which was known to have a record-high fracture toughness. The ZT1 exhibits the highest fatigue endurance limit among all BMGs, with a normalized fatigue limit of sigma(a) = 440 MPa (in four-point bending at a loading ratio of 0.1), or similar to 0.27 of its tensile strength. The crack-growth resistance in the stress/life tests arises from crack-tip plastic shielding due to prolific shear-banding, as well as deflected crack path following a "zig-zag" pattern. The relation between the range of stress intensity factor (Delta K) and the crack-growth rate (crack extension per cycle, da/dN) was also determined. ZT1 shows a fatigue threshold, Delta K-th, of 2.8 MPa root m, which appears to be related to the onset of shear band nucleation. Three distinct regimes of fatigue crack growth were observed, with different slopes in the da/dN-Delta K curve, attributable to different micromechanisms. In the Paris regime, each fatigue striation on fracture surface is generated by a number of loading cycles, rather than by a single loading cycle. In general, the Delta K-th of a BMG approximately scales with its fracture toughness. At different levels of Delta K, shear bands appear to play different roles, either facilitating or blunting the crack growth. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.