Keck Engineering Laboratories, California Institute of Technology, Pasadena, California 91125, USA.
Nat Mater. 2011 Feb;10(2):123-8. doi: 10.1038/nmat2930. Epub 2011 Jan 9.
Owing to a lack of microstructure, glassy materials are inherently strong but brittle, and often demonstrate extreme sensitivity to flaws. Accordingly, their macroscopic failure is often not initiated by plastic yielding, and almost always terminated by brittle fracture. Unlike conventional brittle glasses, metallic glasses are generally capable of limited plastic yielding by shear-band sliding in the presence of a flaw, and thus exhibit toughness-strength relationships that lie between those of brittle ceramics and marginally tough metals. Here, a bulk glassy palladium alloy is introduced, demonstrating an unusual capacity for shielding an opening crack accommodated by an extensive shear-band sliding process, which promotes a fracture toughness comparable to those of the toughest materials known. This result demonstrates that the combination of toughness and strength (that is, damage tolerance) accessible to amorphous materials extends beyond the benchmark ranges established by the toughest and strongest materials known, thereby pushing the envelope of damage tolerance accessible to a structural metal.
由于缺乏微观结构，玻璃态材料本质上强度高但易碎，并且通常对缺陷极为敏感。因此，它们的宏观失效通常不是由塑性屈服引发的，几乎总是以脆性断裂结束。与传统的脆性玻璃不同，金属玻璃通常能够在存在缺陷的情况下通过剪切带滑动实现有限的塑性屈服，从而表现出介于脆性陶瓷和边缘韧性金属之间的韧性-强度关系。在这里，介绍了一种块状玻璃态钯合金，它展示了一种异常的能力，可以屏蔽由广泛的剪切带滑动过程容纳的开口裂纹，从而提高了与已知最坚韧材料相当的断裂韧性。这一结果表明，非晶态材料的韧性和强度（即损伤容限）的组合超出了已知最坚韧和最强材料所建立的基准范围，从而推动了结构金属可达到的损伤容限范围。
