(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 常州大學(xué) 材料科學(xué)與工程學(xué)院，常州 213164；
3. 常州大學(xué) 常州市先進(jìn)金屬重點(diǎn)實(shí)驗(yàn)室，常州 213164)
摘 要: 采用DSC熱分析、硬度、電導(dǎo)率、拉伸和晶間腐蝕等測試及透射電鏡組織觀察，研究Cu含量對Al-Mg-Si-Cu合金微觀組織和性能的影響。實(shí)驗(yàn)表明：180 ℃時(shí)效時(shí)，4種合金硬度上升至峰值后持續(xù)下降，且隨著 Cu含量增加，合金的時(shí)效硬度隨之提高，硬化速率加快而軟化速率降低；時(shí)效時(shí)電導(dǎo)率先下降至最低值后又持續(xù)上升，且Cu含量越高，電導(dǎo)率越低。隨著Cu含量增加，T6和T4態(tài)合金的強(qiáng)度隨之提高，晶間腐蝕抗力下降，但無Cu合金不發(fā)生晶間腐蝕；T6態(tài)合金析出相類型隨Cu含量增加而變化，Cu含量較低時(shí)(0.6以下)，析出β″相；而Cu含量為0.9時(shí)，析出相為β″相和Q′相共存；且隨著Cu含量增加，析出相數(shù)量和體積分?jǐn)?shù)增加而尺寸減小，T4態(tài)合金析出相為原子團(tuán)簇。
關(guān)鍵字: Al-Mg-Si-Cu合金；Cu含量；析出相；晶間腐蝕；拉伸性能
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
3. Key Laboratory of Advanced Metal Materials of Changzhou City, Changzhou University, Changzhou 213164, China）
Abstract:The microstructures and properties of Al-Mg-Si-Cu alloys were investigated by differential scanning calorimetry, Vickers hardness, electrical conductivity, tensile properties test, intergranular corrosion and transmission electron microscopy. The hardness of the alloys aged at 180 ℃ increases to a peak value and decreases subsequently. The hardening rates of the alloys increase with the increase of Cu content, and the softening rate decreases due to overageing. The electrical conductivity of the alloys firstly decreases to a minimum value and increases subsequently. The electrical conductivity decreases with the increase of Cu content. With the Cu content increasing, the tensile strengths of the alloys in T6 and T4 increase, and the resistance to intergranular corrosion decreases, but the alloy without Cu does not present intergranular corrosion sensitivity. The kind of the precipitates in the T6 alloy varies with the Cu content increasing. β″ phase dominates in the alloys at the Cu content lower than 0.6, but β″ and Q′ coexist in the alloys with Cu content of 0.9. The number density and volume fraction of the precipitates increase with the increase of Cu content and the size decreases. The precipitates are solute clusters in the T4 alloy.
Key words: Al-Mg-Si-Cu alloy; Cu content; precipitate phase; intergranular corrosion; tensile property
