【摘要】 采用液相包裹法对亚微米Al2O3颗粒进行稀土表面改性,用挤压铸造法制备表面经稀土改性的Al2O3p/6061Al复合材料.对颗粒表面经稀土改性前后增强6061Al复合材料在不同温度下的时效析出行为进行分析研究.结果表明:改性后的亚微米Al2O3粉体颗粒表面Y2O3包裹均匀,其增强的复合材料在不同时效阶段的硬度值均较改性前有明显提高.且随着时效温度的升高,Mg2Si析出过程加快,时效峰提前,呈现出硬度值变小的趋势.透射电镜观察表明,表面改性颗粒增强的复合材料基体中存在一定量的位错和析出相;而改性前复合材料却呈现出位错和析出相极其稀少的组织特征.分析了改性前后复合材料时效组织形成的原因.更多还原

【Abstract】 Liquid coated approach was used in rare-earth modification on the surface of sub-micron Al2O3 particles, and a 6061 Al matrix composite reinforced by the modified Al2O3 particles was fabricated using squeeze-casting technique. The aging precipitation behaviors of sub-micron Al2O3p/6061Al composites before and after modification of Al2O3 particles at different aging temperatures were analysed. The results indicate that the modified sub-micron Al2O3 particle surfaces are coated homogeneously and the hardness of the modified-Al2O3p/6061Al composite is obviously increased comparing to the as-received Al2O3p/6061Al at different aging states. With increasing of temperature the precipitation processes (Mg2Si) become accelerated, the time to reach the peak hardness is shortened and the hardness peak value is reduced. TEM observation of the aging microstructure shows that some dislocations and precipitates exist in Al-matrix of modified-Al2O3p/6061Al composite, but only rare dislocation and precipitates exist in as-received Al2O3p/6061Al. The reasons of the above aging microstructure difference are discussed.更多还原