The distribution and size of particles in particle-reinforced aluminum matrix composites are crucial to the mechanical properties of the composites. In this paper, 2 wt.% TiB₂/2195 composites were prepared by ultrasonic-assisted in-situ casting technology, and the samples' phase composition, microstructure, and mechanical properties were tested. The results showed that: compared with the remelted matrix, the stomatal defects in the composites disappeared, and the grains were refined, but the second phase structure and TiB₂ particles agglomerated significantly when no ultrasonic treatment (UT) was applied. The UT made the grains further refined, the area fraction of the coarse second phase network decreased, the concentrations of Ti and Cu elements in the grains increased, and more TiB₂ particles entered the grains. At the same time, the formation of TiB₂ particles and UT increased the dislocation density in the composites and promoted the precipitation of the T1 phase. With UT for 180 s, the TiB₂ particles were evenly distributed, and the size was the smallest. The tensile strength, yield strength, and elongation were increased by 115.4 %, 49.8 %, and 342.9 %, respectively, compared to the remelted matrix, and by 30.9 %, 21.8 %, and 67.2 %, respectively, compared to the composite without UT. The mechanism of the synergistic effect of UT and TiB₂ to enhance the mechanical properties of composites was also discussed.

颗粒增强铝基复合材料中颗粒的分布和尺寸对复合材料的力学性能至关重要。本文采用超声辅助原位铸造技术制备了2 wt.% TiB _{2 /2195复合材料，并对样品的物相组成、微观结构和力学性能进行了测试。}结果表明：与重熔基体相比，未进行超声处理（UT）时，复合材料气孔缺陷消失，晶粒细化，但第二相组织和TiB _{2颗粒明显团聚。}UT使晶粒进一步细化，粗大第二相网络的面积分数降低，晶粒中Ti和Cu元素浓度增加，更多的TiB_2个颗粒进入晶粒。同时，TiB ₂颗粒和UT的形成增加了复合材料中的位错密度，促进了T1相的析出。UT 180 s，TiB ₂颗粒分布均匀，尺寸最小。与重熔基体相比，抗拉强度、屈服强度和伸长率分别提高了 115.4%、49.8% 和 342.9%，与没有 UT 的复合材料相比，分别提高了 30.9%、21.8% 和 67.2% . 还讨论了UT与TiB ₂协同作用提高复合材料力学性能的机理。