Abstract

In this investigation, TiC reinforcements were incorporated into Al-Zn-Mg-Cu alloy by integrating reverse engineering and geometry reconstruction technique with a surface composite being developed through the recursive method of friction stir processing (FSP). The fabricated composite was further subjected to T6 and RRA heat treatments and its microstructural changes, mechanical and tribological properties examined. Microstructural studies revealed the formation of well refined equiaxed grain structure with a reduced average grain size of 2.40 µm for the FSPed composite and 2.90 and 3.03 µm for T6 and RRA heat treated composites, indicating that grain growth and recrystallization were inhibited effectively by the presence of uniformly dispersed TiC particles during FSP and heat treatments. Improved distribution of hardness with an average of 208.64 HV was observed for the FSPed composite. After T6 and RRA treatments, average hardness was enhanced to 244.29 and 230.26 HV due to the additional strengthening caused by the precipitates. Tribological investigations revealed better wear resistance for the heat treated composites compared to the as-FSPed composite. The presence of a hardened surface with TiC rich tribo-layer and finely distributed precipitates stifled the extent of plastic deformation and improved wear resistance.

摘要

在这项研究中，通过将逆向工程和几何重构技术与通过摩擦搅拌处理 (FSP) 的递归方法开发的表面复合材料相结合，将 TiC 增强材料加入到 Al-Zn-Mg-Cu 合金中。制造的复合材料进一步经受 T6 和 RRA 热处理，并检查其微观结构变化、机械和摩擦学性能。显微组织研究表明，FSPed 复合材料的平均晶粒尺寸减小了 2.40 µm，T6 和 RRA 热处理复合材料的平均晶粒尺寸减小了 2.90 和 3.03 µm，表明形成了精细的等轴晶粒结构，表明晶粒长大和再结晶受到有效抑制。在 FSP 和热处理过程中均匀分散的 TiC 颗粒。改善硬度分布，平均为 208。对于 FSPed 复合材料，观察到 64 HV。经过 T6 和 RRA 处理后，由于析出物引起的额外强化，平均硬度提高到 244.29 和 230.26 HV。摩擦学研究表明，与 FSPed 复合材料相比，热处理复合材料具有更好的耐磨性。具有富含 TiC 的摩擦层和精细分布的沉淀物的硬化表面的存在抑制了塑性变形的程度并提高了耐磨性。