多重纳米结构轻质高强铝基复合材料的制备和组织性能

Preparation and Investigation of Microstructure and Mechanical Properties of Ultra-high Strength Al Alloy Matrix Composites with Hybrid Nanostructure

为了研究多重纳米结构对块体材料强化和变形能力的影响机制,采用粉末冶金法制备了多重纳米结构的B4C颗粒增强铝基复合材料,并对复合材料的强化和形变破坏机制进行了定量和定性的讨论。由100%球磨复合粉末制备的块体复合材料的室温压缩强度为670MPa;当加入10vol%气雾化态的Al2024粉末后,复合材料的室温压缩强度升高到1.115GPa;之后随着气雾化态Al2024粉末含量的增加,复合材料的强度逐渐下降,但是没有产生明显的塑性变形;当气雾化态Al2024粉末的含量增加到50vol%时,复合材料的压缩强度下降到580MPa,断裂前变形率达到了10%。扫描电镜(SEM)和透射电镜(TEM)的分析结果显示,亚微米级的B4C颗粒、位错以及纳米晶基体分别通过Orowan强化、位错强化和细晶强化机制对复合材料进行强化;粗晶Al2024区域与复合结构区域的比例显著影响复合材料的形变及破坏机制。

B4 C particles reinforced Al2024 matrix composites were fabricated by using powder metallurgy method,in order to study the effect of hybrid nanostructure on the strengthening,deformation and fracture mechanisms of the composites.The composites made from 100％ mechanical milled composite powders have fracture strength of 670 MPa.When mixing with 10vol％ un-milled Al2024 powder,the room temperature compression strength of the composites is increased to 1.115 GPa.After that,the room temperature compression strength of the composites decreases with the increase of the content of unmilled Al2024 powder,and the composites show no visible plastic deformation.However,when the fraction of un-milied Al2024 powder increases to 50vo1％,the compression strength is decreased to 580 MPa,while retaining a remarkable fracture strain up to 10 ％.The microstructures of the composites with different compositions were examined by scanning electron microscope （SEM） and transmission electron microscope （TEM）.The results show that sub-micro sized B4C particles,dislocations and nano-crystalline matrix enhance the strength of the composites through Orowan strengthening,dislocation strengthening and grain refinement strengthening,respectively.The ratio between coarse-grained region and composites region has a significant effect on the deformation and fracture behavior of the composites.