材料期刊网

采用挤压铸造方法制备了Bi₂O₃涂覆Al₁₈B₄O₃₃晶须增强的铝基复合材料. 探讨了Bi₂O₃含量、应变振幅、温度以及频率对涂覆复合材料阻尼性能的影响. 并对涂覆后复合材料的阻尼机制作了初步的探讨.研究发现, 涂覆复合材料在80和285℃附近存在2个明显的阻尼峰. 涂覆复合材料的阻尼性能不仅强烈依赖于晶须表面涂覆物的含量, 而且依赖于应变振幅. 高温阻尼峰P2随涂覆物含量及应变振幅增加而提高的幅度更大. 低温阻尼峰P1在涂覆复合材料中的阻尼机制归因于位错运动及由Bi引起的界面滑移. 阻尼峰P2随应变振幅的增加阻尼机制由界面滑移机制向界面滑移与Al晶界滑移混合机制转变.

In metal matrix composites (MMCs), the reinforcement/matrix interface has a profound effect on its overall properties. The proper selection or design of the interfacial phase plays a vital role in optimizing the final properties of MMCs, in which high damping capacity is one of the most important properties of materials used in engineering structure. Although the damping mechanism of discontinuously reinforced aluminum composites has been extensively studied, only a few of researches have been reported on the effect of whisker coatings on the damping capacity of MMCs. In this paper, the pure aluminum matrix composites reinforced by alumina borate (Al₁₈B₄O₃₃) whisker with and without Bi₂O₃ coatings were separately fabricated by squeeze and the volume fraction of Al₁₈B₄O₃₃ whisker in these composites is about 20%. The mass ratios between Al₁₈B₄O₃₃ whisker and Bi₂O₃ were set as 6∶1, 10∶1 and 20∶1, respectively. The effects of coating contents and strain amplitudes on the damping properties of the coated composites at various temperatures and frequencies were examined. Two damping peaks (P1 and P2) in the coated composites at around 80 and 285 ℃ were observed. The results of damping characterization indicate that the damping capacity of the coated composites strongly depends on the content of coatings and strain amplitudes. Moreover, P2 increases more rapidly with increasing the coating content and strain amplitude. P1 is related to dislocation motion and interfacial slip between the whisker and Bi phase. The damping mechanism of P2 changes with the increase of stain amplitude.