The fracture behavior of high-temperature co-sputtered Cu/Mo nanocomposite thin films was investigated through in situ 3-point bend testing of pre-notched microbeams in SEM. The as-synthesized nanocomposites present hierarchical nano/microstructures composed of a matrix of phase-separated Cu–Mo with nanoscale ligaments dispersed with sub-micron scale Cu-rich islands containing Mo nano-precipitates. Results show a significant crack growth resistance in the hierarchical nanocomposite, several times higher than that measured in Cu/Mo nanoscale multilayers. Based on electron microscopy characterization, three mechanisms of crack growth resistance in the hierarchical structures are proposed: crack bridging by the Cu-rich layer, crack deflection via shear along the Cu/Mo interface, and multiple cracking. This work demonstrates an approach to increase toughness in high strength nanocomposites through interface micro-structure design.

通过原位研究了高温共溅射Cu / Mo纳米复合薄膜的断裂行为。SEM中的预刻痕微束的三点弯曲测试。合成后的纳米复合材料呈现出分层的纳米/微观结构，由相分离的Cu-Mo矩阵组成，纳米级韧带分散在亚微米级富Cu岛中，其中包含Mo纳米沉淀。结果表明，在分层纳米复合材料中，显着的抗裂纹扩展性比在Cu / Mo纳米级多层中测得的抗裂性高出几倍。基于电子显微镜表征，提出了分层结构中抗裂纹扩展的三种机理：富铜层的桥接，通过剪切沿铜/钼界面的挠曲和多重开裂。这项工作演示了一种通过界面微结构设计提高高强度纳米复合材料韧性的方法。