| 摘要: | 本研究藉由微結構、拉伸試驗、慢速拉伸試驗(SSRT)與極化電位試驗，探討微量Cu對於原生Al-Zn-Mg合金與100%再生商用Al-Zn-Mg合金、之機械性質與抗應力腐蝕性的影響。研究中將以原生Al-Zn-Mg(-Cu)合金作為對照組，對比分析未添加Cu與添加0.2 wt% Cu的合金在不同回收比例下的性能差異。
結果顯示，微量Cu的添加可顯著提升原生與100%再生Al-Zn-Mg合金的強度與抗腐蝕性能。在微結構分析中，Cu的添加提升了α-Al基地中η´-MgZn₂強化相的析出量，使合金的抗拉強度明顯增加，增強其機械性質。同時，Cu的添加提高了晶界析出相(η-MgZn₂平衡相)的Cu含量，進而提升其腐蝕電位，減少與α-Al基地之間的電位差，降低伽凡尼腐蝕的發生率，從而顯著提升合金的抗腐蝕能力。
然而，100%再生Al-Zn-Mg(-Cu)合金因α-Al基地中含有損害機械性質的β富鐵相，導致其延性略有下降，並增加合金在腐蝕環境中發生點蝕的可能性。但整體而言，100%回收與非回收的Al-Zn-Mg(-Cu)合金、在強度與抗腐應力腐蝕性相近，證明回收合金的應用潛力。
總結而言，微量Cu的添加不僅有效提升原生與回收Al-Zn-Mg合金的強度與抗腐蝕性能，還顯著改善回收合金的綜合性質，為回收鋁合金的工業應用提供了重要參考。
關鍵詞: Al-Zn-Mg合金、回收比、Cu含量、應力腐蝕
;This study investigates the effects of trace Cu on the mechanical properties and stress corrosion resistance of primary Al-Zn-Mg alloys and 100% recycled commercial Al-Zn-Mg alloys through microstructural analysis, tensile testing, slow strain rate testing (SSRT), and polarization potential testing. The primary Al-Zn-Mg(-Cu) alloy serves as a control group in the study, with a comparative analysis conducted on the performance differences between alloys with no Cu addition and those containing 0.2 wt% Cu across varying recycling ratios.
The results demonstrate that the addition of trace Cu significantly enhances the strength and corrosion resistance of both primary and 100% recycled Al-Zn-Mg alloys. Microstructural analysis reveals that Cu addition increases the precipitation of the η´-MgZn₂ strengthening phase within the α-Al matrix, thereby significantly improving the tensile strength and mechanical properties of the alloy. Furthermore, the addition of Cu raises the Cu content in the η-MgZn₂ equilibrium phase at grain boundaries, which, in turn, elevates the corrosion potential, reduces the potential difference with the α-Al matrix, and decreases the occurrence of galvanic corrosion, thereby markedly improving the corrosion resistance of the alloy.
However, the presence of β-Fe-rich phases in the α-Al matrix of 100% recycled Al-Zn-Mg(-Cu) alloys slightly reduces ductility and increases the likelihood of pitting corrosion in corrosive environments. Nonetheless, the overall strength and stress corrosion resistance of the 100% recycled and primary Al-Zn-Mg(-Cu) alloys are comparable, underscoring the application potential of recycled alloys.
In summary, the addition of trace Cu not only effectively enhances the strength and corrosion resistance of both primary and recycled Al-Zn-Mg alloys but also significantly improves the overall properties of recycled alloys, providing valuable insights for the industrial application of recycled aluminum alloys.
Keywords: Al-Zn-Mg alloys, recycling ratio, Cu content, stress corrosion. |
