Nanocomposite materials containing a soft and hard metal phase are a promising strategy to combine ultra-high strength, ductility and fracture toughness. However, given the rather brittle intercrystalline fracture mode, the true potential of these materials is only accessible after strengthening the vast number of interfaces within the composite. In this work, this is realized by doping a W–75Cu nanocomposite with either C, B, Hf or Re, elements that show promising effects on grain boundary cohesion in ab-initio calculations. The samples are fabricated from powders using severe plastic deformation and characterized using electron microscopy. Subsequently, various small-scale mechanical experiments are utilized to investigate the effect of the doping on strength, ductility and fracture toughness. While doping with C and B only leads to slight changes in mechanical properties, it was found that Hf increases the strength of the composite tremendously, most likely via the formation of nanosized oxides. Doping with Re showed an increase in strength and a major improvement in bending ductility, exhibiting “super-ductile” behavior in some cases. In microtensile tests this behavior was reduced, yet an increase in strength and ductility compared to the undoped composite was also apparent in these experiments. Interestingly enough, the fracture toughness of all doped variants did not change compared to the undoped W–Cu composite. This indicates that doping with Re improves resistance against crack initiation but not against crack propagation, making the materials properties highly sensitive to pre-existing defects and probed sample volume.

含有软硬金属相的纳米复合材料是一种结合超高强度、延展性和断裂韧性的有前途的策略。然而，鉴于相当脆的晶间断裂模式，这些材料的真正潜力只有在强化复合材料内的大量界面后才能获得。在这项工作中，这是通过在 W-75Cu 纳米复合材料中掺杂 C、B、Hf 或 Re 来实现的，这些元素在从头算计算中显示出对晶界凝聚力的良好影响。样品是使用严重的塑性变形由粉末制成的，并使用电子显微镜进行表征。随后，利用各种小规模机械实验来研究掺杂对强度、延展性和断裂韧性的影响。虽然掺杂 C 和 B 只会导致机械性能发生轻微变化，但发现 Hf 极大地提高了复合材料的强度，很可能是通过形成纳米级氧化物。掺杂 Re 显示出强度的增加和弯曲延展性的重大改进，在某些情况下表现出“超延展性”行为。在微拉伸试验中，这种行为有所减少，但与未掺杂的复合材料相比，强度和延展性的增加在这些实验中也很明显。有趣的是，与未掺杂的 W-Cu 复合材料相比，所有掺杂变体的断裂韧性都没有变化。这表明掺杂 Re 可提高抗裂纹萌生能力，但不能提高裂纹扩展能力，从而使材料性能对预先存在的缺陷和探测样品体积高度敏感。