7xxx系鋁合金為高強度的析出強化型合金，因具有較其他系列鋁合金高的強度及破壞韌性等優點，目前廣泛應用於國防、航太及汽車等工業。由前人研究的結果顯示高鎂含量的7075與7050合金經摩擦攪拌製程 (FSP)後拉伸性質大多都會發生劣化的情況，但對於低鎂含量之合金並未深入探討，因此本實驗選定低鎂含量的商用材7005 (依其Zn/Mg比命名為ZM35)進行FSP，攪拌後接著再進行數種人工時效，觀察拉伸性質之變化。此外，為觀察不同Zn/Mg比合金FSP後性質變化是否相似，本實驗另外以ZM57 (Zn:Mg=6.34:1.11)進行上述試驗。
實驗結果顯示，ZM35與ZM57合金經時效達穩定之攪拌材強度同樣有劣化的情形，其中兩種合金降伏強度之劣化率皆高於30%，抗拉強度劣化率約為10%；延性方面反而有提升的效果，兩種合金皆可提升至20%左右。攪拌後進行數種人工時效雖可改善強度劣化之情況，但仍不及攪拌母材。
數種人工時效處理中，ZM35與ZM57合金經一階段 (40℃/96hr與80℃/16hr)與二階段 (80℃/16hr+T6)處理，有相似的拉伸性質變化，其中二階段處理可大幅改善強度劣化之情況。然而兩種合金經三階段 (T4+80℃/16hr+T6)處理後拉伸性質會明顯有不同的變化，對ZM35合金而言，強度會較二階段處理再略為提升，但同樣低於攪拌母材，延性則會再次下降；但ZM57合金之強度與延性皆會下降，其中延性的劣化率甚至高達60%。

The precipitation-hardening 7xxx series aluminum alloys are widely used in the aircraft and military industry, due to the higher strength and fracture toughness than other series aluminum alloys. Now the most researches about friction stir process focus more on high Mg content 7050 and 7075 alloy, which showed the tensile properties would be worse than the base metal (T6 treatment), but less on low Mg content alloys. In this study, we are aimed to observe the change of tensile properties by several artificial aging treatments on friction stir processed low Mg content commercial 7005 Al alloy, which is also called ZM35 because of its Zn/Mg ratio. In order to compare with ZM35, we also use the same process on ZM57 alloy which has different Zn/Mg ratio.
After the process of friction stir and then natural aging for 12 days, the experiment results show that the strength of ZM35 and ZM57 would be deteriorated compared to base metal. The deterioration rate of YS is more than 30% and UTS is about 10%, but the ductility is raised to 20% instead. Thus, after the several artificial aging treatments, the strength of the material which is as-FSP condition could be promoted, but it still worse than base metal.
In the several artificial aging treatments, one-step (40℃/96hr and 80℃/16hr) and two-step (80℃/16hr+T6) treatments exhibit the similar results for ZM35 and ZM57 alloys. In addition, the strength of the material which is as-FSP condition could be improved by using two-step treatments. After three-step (T4+80℃/16hr+T6) treatment, the tensile properties have different results in ZM35 and ZM57 alloys: for ZM35, the strength became better and the ductility got worse than two-step treatments; for ZM57, the strength and the ductility both decreased, and the deterioration rate of the ductility even reached 60%.

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