仿贝壳TiB_(2)/Al-Cu层状复合材料的组织及其力学性能

Microstructure and mechanical properties of nacre-inspired TiB_(2)/Al-Cu composites

陶瓷增强铝基复合材料是轻量化结构件的较理想材料,但随着陶瓷增强相含量的增加,复合材料的韧性会降低,导致复合材料服役过程中安全性的下降。因此如何实现复合材料高强韧性的匹配是制备陶瓷增强铝基复合材料一直存在的难题。根据仿生学思想,采用冷冻铸造及压力浸渗技术制备了不同陶瓷初始固相含量(20vol%、30vol%、40vol%)的TiB_(2)/Al-Cu层状复合材料。采用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析(XRD)和力学性能测试研究了不同陶瓷初始固相含量对于TiB_(2)/Al-Cu层状复合材料微观组织和力学性能的影响。实验结果表明,随着陶瓷初始固相含量的提升,复合材料中陶瓷片层厚度增加,金属片层厚度减小,复合材料的抗压强度有所提升但抗弯强度和断裂韧性下降。其中,20vol%陶瓷初始固相含量的TiB_(2)/Al-Cu层状复合材料拥有较优的断裂韧性,达到了(20.59±1.5)MPa·m^(1/2);40vol%陶瓷初始固相含量制备的TiB_(2)/Al-Cu层状复合材料拥有较优的抗压强度,达到了(670±20)MPa。这主要是因为随着复合材料中陶瓷初始固相含量的提升,层状复合材料更容易发生界面脱层,层状复合材料通过合金塑性变形等增韧效果减弱;同时,裂纹偏折、界面剥落、裂纹分支等增韧效果也降低。

Ceramic-reinforced aluminum-based composites are ideal materials for lightweight structural parts.However,as the content of the ceramic reinforcement phase increases,the toughness of the composites will decrease,resulting in a decrease in the safety of the composites during service.Therefore,how to achieve the matching of high strength and toughness of composite materials is a problem that has always existed in the preparation of ceramic reinforced aluminum matrix composites.According to the idea of bionics,the nacre-inspired TiB_(2)/Al-Cu composites with different ceramic initial solid contents(20vol%,30vol%,40vol%)were successfully prepared by freezing casting and pressure infiltration.The microstructures and mechanical properties of nacre-inspired TiB_(2)/AlCu composites were studied by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD)and mechanical testing.The experimental results show that with the increase of the initial solid content of the ceramic,the thickness of the ceramic sheet in the composite material increases,while the thickness of the metal sheet layer decreases.The compressive strength of the composite material is improved,but the bending strength and fracture toughness decrease.The nacre-inspired TiB_(2)/Al-Cu composites with 20vol% ceramic initial solid content has the better fracture toughness,reaching(20.59±1.5)MPa·m^(1/2).The nacre-inspired TiB_(2)/Al-Cu composites with 40vol% ceramic initial solid content has the better compressive strength,reaching(670±20)MPa.This is mainly because as the initial solid content of the ceramic in the composite material increases,the nacre-inspired composite material are more prone to interface delamination,the toughening effect of the layered composite material through alloy plastic deformation is weakened.At the same time,the toughening effect of crack deflection,interface peeling,and crack branching is reduced.