Aluminum-matrix nanocomposites offer advantageous properties over conventional aluminum alloys. However, controlling the size and size distribution of ceramic nanoparticles during in situ synthesis at high temperatures has been a long-term challenge due to a lack of effective size-control mechanisms. Here, we successfully synthesized titanium diboride (TiB₂) nanoparticles with an unprecedented narrow size distribution in molten aluminum. The average size of TiB₂ nanoparticles was tunable from 22.1 to 171.4 nm by solely controlling the reaction temperature under a diluted reactant salt solution. To uncover the mechanism of particle size control, an interface diffusion-controlled model was developed. The dilution of reactant salt was crucial to achieve a steady reaction environment while confining the growth of the particles in a shallow region. The model suggests that the average size of as-synthesized nanoparticles is mostly controlled by reaction temperature and unaffected by the titanium salt concentration in a diluted solution due to a steady diffusion of titanium and boron. Temperature controls the diffusion of reactants and nucleation rate to dictate the average size of the as-synthesized nanoparticles.

铝基纳米复合材料提供了优于常规铝合金的有利性能。然而，由于缺乏有效的尺寸控制机制，在高温下原位合成过程中控制陶瓷纳米粒子的尺寸和尺寸分布是一项长期的挑战。在这里，我们成功地在熔融铝中合成了前所未有的窄尺寸分布的二硼化钛（TiB ₂）纳米粒子。TiB ₂的平均大小通过仅在稀释的反应盐溶液中控制反应温度，可将纳米颗粒从22.1调节至171.4 nm。为了揭示粒径控制的机理，建立了界面扩散控制模型。反应物盐的稀释对于实现稳定的反应环境同时将颗粒的生长限制在浅区域是至关重要的。该模型表明，合成后的纳米颗粒的平均尺寸主要受反应温度控制，而不受钛和硼稳定扩散的稀释溶液中钛盐浓度的影响。温度控制反应物的扩散和成核速率，以决定合成后纳米颗粒的平均尺寸。