Nanoparticles have been widely used to tune the mechanical, thermophysical, and chemical properties of materials for widespread applications ^1-3. Despite achieving other unprecedented functionalities, metals containing ceramic nanoparticles often suffer a significant loss in thermal conductivity with theoretical upper limits set by the Hashin-Shtrikman (with interfacial interactions) and Weiner (without interfacial interactions) models. Here, we discover that the Cu-60Ag alloy with 10 vol% WC nanoparticles delivers a surprisingly high thermal conductivity, breaking the theoretical upper limits. To understand the underlying mechanisms, thermal transport contributions from phonons and electrons, as well as microstructure, are studied. The study suggests that there exists an unusual enhancement of thermal transport in Cu-60Ag by the less conductive WC nanoparticles. Though thermal analysis including 3ω-method may be needed to decouple influencing factors, this new finding is of significance for development and application of nanoparticles reinforced metals with both superior mechanical strength and high thermal conductivity.

纳米粒子已被广泛用于调整材料的机械，热物理和化学性质，以广泛应用^1-3。尽管实现了其他前所未有的功能，但包含陶瓷纳米粒子的金属通常会遭受明显的热导率损失，其理论上限由Hashin-Shtrikman（具有界面相互作用）和Weiner（无界面相互作用）模型设定。在这里，我们发现具有10％（体积）WC纳米颗粒的Cu-60Ag合金具有惊人的高导热率，打破了理论上限。为了理解潜在的机理，研究了声子和电子的热传输贡献以及微观结构。研究表明，导电性较低的WC纳米颗粒在Cu-60Ag中存在异常的热传输增强。尽管可能需要包括3ω方法在内的热分析来分离影响因素，