形變時效組合工藝與Al-1.0Mg-0.5Si-0.8Cu合金腐蝕行為和微觀結構的關系

陳江華 鄧東慧 賴玉香 劉力梅

摘? ?要：采用硬度測試、晶間腐蝕實驗、慢應變速率拉伸實驗和TEM表征等手段，選取自然時效、欠人工時效和峰值人工時效3種預時效系統研究了預時效對形變時效組合工藝制備的Al-Mg-Si-Cu合金抗腐蝕性能和微觀結構的影響.結果表明：預時效可以調控合金的硬度和抗腐蝕性能，3種預時效處理中峰值人工時效預處理使合金獲得了硬度（159 HV）和抗腐蝕性能（最大晶間腐蝕深度為55 μm，應力腐蝕敏感指數Iδ為8.3%）的最優結合. TEM結果顯示，冷軋引入的高密度位錯有效提高了合金的硬度;晶內析出大量納米級富Cu的板條狀Q"相或彎曲連續狀析出相，消除了晶界析出相的形成，并大大降低了基體與PFZ之間的電位差，因此顯著提高了合金的抗腐蝕性能.自然時效、欠人工時效和峰值人工時效預處理的合金晶內析出程度依次增大，基體與PFZ之間的電位差依次減小，合金的抗腐蝕性能依次升高.

關鍵詞：Al-Mg-Si-Cu合金;形變;時效;腐蝕;位錯;析出

中圖分類號：TG113;TG166.3;TG156.9? ? ? ? ? ? 文獻標志碼：A

Study of Correlation Between Combined Deformation

and Aging Process as well as Corrosion Behavior

with Microstructure of Al-1.0Mg-0.5Si-0.8Cu Alloy

CHEN Jianghua，DENG Donghui，LAI Yuxiang，LIU Limei

（College of Materials Science and Engineering，Hunan University，Changsha? 410082，China）

Abstract：Three pre-aging treatments of natural aging， artificial under-aging and artificial peak-aging were chosen to systematically investigate the influence of pre-aging on the corrosion resistance and microstructure of an Al-1.0Mg-0.5Si-0.8Cu alloy produced by combined cold-rolling and aging process using hardness measurement， intergranular corrosion test， slow strain rate technique， and transmission electron microscopy （TEM）. The results show that pre-aging can tune the hardness and corrosion resistance of the alloy. Among the three pre-aging treatments， the artificial peak-aging treatment results in the optimal combination of hardness（being 159 HV） and corrosion resistance（with the maximum intergranular corrosion depth of 55 μm and the stress corrosion cracking susceptibility index Iδ of 8.3%）. The TEM results reveal that the high density of dislocations efficiently enhances the hardness of the alloy. Numerous nano-sized Cu-rich lath-like Q" precipitates or curved continuous precipitates are distributed in the matrix， which eliminate the formation of grain boundary precipitates and greatly reduce the electrochemical potential difference between the matrix and PFZ，consequently significantly improving the corrosion resistance of the alloy. In the alloys pre-aged by natural aging， artificial under-aging and artificial peak-aging， the degree of precipitation in the matrix increases in sequence， so that the electrochemical potential difference between the matrix and PFZ decreases in sequence. Therefore， the corrosion resistance of the alloy is improved in sequence.

Key words：Al-Mg-Si-Cu alloy;deformation;aging;corrosion;dislocation;precipitation