Microstructures and mechanical properties of in-situ TiB₂ reinforced Al-xZn-2.5Mg-2.4Cu-0.15Zr composites with different Zn content (i.e. x = 6.9, 9 and 12 wt%) were studied in this work. Detailed microstructural investigations have been carried out via scanning electron microscopy and associated orientation imaging microscopy. The results indicate that as Zn content increased from 6.9 to 12 wt%, the severe clusters of TiB₂ particles were noticeably dispersed owing to the decreased interfacial energy between TiB₂ particles and Al matrix. The average grain size of extruded samples decreases and the grain shapes tend to be more equiaxed with the increase of Zn content, thanks to the formation of LAGBs and its transformation to HAGBs surrounding dispersed TiB₂ particles in the grain. In addition, the yield strength of extruded samples increases from 597 MPa to 707 MPa with the increase of Zn content from 6.9 to 12 wt%, via grain-boundary strengthening mechanism and reinforcing particles strengthening mechanism.

本文研究了不同Zn含量（即x = 6.9、9和12 wt％）的原位TiB ₂增强Al-xZn-2.5Mg-2.4Cu-0.15Zr复合材料的组织和力学性能。已经通过扫描电子显微镜和相关的取向成像显微镜进行了详细的微观结构研究。结果表明，随着Zn含量从6.9 wt％增加到12 wt％，由于TiB ₂颗粒与Al基体之间的界面能降低，严重的TiB ₂颗粒簇明显分散。挤压样品的平均晶粒尺寸减小，并且随着锌含量的增加，晶粒形状趋于更加等轴，这要归功于LAGBs的形成以及它在分散的TiB周围转变为HAGBs的结果。谷物中有_2个颗粒。另外，通过晶界强化机制和强化颗粒强化机制，随着Zn含量从6.9wt％增加到12wt％，挤压样品的屈服强度从597 MPa增加到707 MPa。