摘要
To address the issue that B_(4)C ceramics are difficult to be wetted by aluminum metals in the composites,TiB_(2)was introduced via an in-situ reaction between TiH_(2)and B_(4)C to regulate their wettability and interfacial bonding.By pressure infiltration of the molten alloy into the freeze-cast porous ceramic skeleton,the 2024Al/B_(4)C-TiB_(2)composites with a laminate-reticular hierarchical structure were produced.Compared with 2024Al/B_(4)C composite,adding initial TiH_(2)improved the flexural strength and valid fracture toughness from(484±27)to(665±30)MPa and(19.3±1.5)to(32.7±1.8)MPa·m^(1/2),respectively.This exceptional damage resistance ability was derived from multiple extrinsic toughening mechanisms including uncracked-ligament bridging,crack branching,crack propagation and crack blunting,and more importantly,the fracture model transition from single to multiple crack propagation.This strategy opens a pathway for improving the wettability and interfacial bonding of Al/B_(4)C composites,and thus produces nacre-inspired materials with optimized damage tolerance.
为了解决复合材料中B_(4)C陶瓷相难以被金属铝润湿的问题,利用TiH_(2)和B_(4)C的原位反应引入TiB_(2),进而调节其润湿性和界面结合。通过将熔融合金压力浸渗到冷冻铸造法制备的多孔陶瓷支架中,制备具有层状结构的2024Al/B4C-TiB_(2)复合材料。与2024Al/B_(4)C复合材料相比,加入TiH_(2)后复合材料的抗弯强度和裂纹扩展韧性分别由(484±27)MPa提高到(665±30)MPa和由(19.3±1.5)MPa·m^(1/2)提高到(32.7±1.8)MPa·m^(1/2)。这种优异的抗损伤能力来自于多重外在增韧机制,包括未开裂韧带的桥接、裂纹分叉、裂纹扩展和裂纹钝化,更重要的是,断裂模式从单一裂纹扩展转变为多裂纹扩展。这一策略为改善Al/B_(4)C复合材料的润湿性和界面黏结性开辟了一条道路,从而生产出具有优良耐损伤性能的仿珍珠贝壳状材料。
基金
financially supported by the National Natural Science Foundation of China(Nos.51502053,52072091,51621091)
Heilongjiang Touyan Team,China。
