(1. 中南大學(xué) 高性能復(fù)雜制造國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
2. 中南大學(xué) 機(jī)電工程學(xué)院，長沙 410083)
摘 要: 通過開展正負(fù)交變電脈沖輔助時效實(shí)驗(yàn)，采用TEM分析以及電導(dǎo)率、維氏硬度和力學(xué)性能等測試手段，研究不同頻率的正負(fù)交變電脈沖對7075鋁合金組織和性能的影響。結(jié)果表明：頻率為10和700 Hz的正負(fù)交變電脈沖可加速時效析出進(jìn)程，顯著提高鋁合金硬度；同時，經(jīng)過正負(fù)交變電脈沖時效熱處理后，試樣的強(qiáng)度較常規(guī)時效熱處理后試樣的強(qiáng)度提高了10.3%，伸長率提高了3.1%；通過TEM對7075鋁合金的顯微組織進(jìn)行觀察，發(fā)現(xiàn)與常規(guī)時效熱處理相比，在正負(fù)交變電脈沖時效熱處理條件下，晶內(nèi)析出相η′的數(shù)量增多，彌散度增高；晶界析出相由細(xì)小連續(xù)分布向斷續(xù)分布的粗化沉淀相轉(zhuǎn)變。可見，正負(fù)交變電脈沖輔助時效熱處理比常規(guī)時效熱處理工藝對鋁合金組織和性能的改善效果更加明顯。
關(guān)鍵字: 7075鋁合金；正負(fù)交變電脈沖；時效熱處理；力學(xué)性能；顯微組織
（1. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China）
Abstract:The positive and negative alternating electrical impulse aging experiments were conducted to study the influence of positive and negative alternating electrical impulse on the microstructure and mechanical properties of 7075 aluminum alloy by TEM analysis, conductivity, Vickers hardness and mechanical properties measurement. The results show that the positive and negative alternating electrical impulse with frequencies of 10 and 700 Hz can accelerate the aging precipitation process and obviously increase the hardness of aluminum alloy. Compared with conventional aging heat treatment, the positive and negative alternating electrical impulse aging heat treatment can improve the strength of the specimen by 10.3% and the elongation of the specimen by 3.1%. Meanwhile, the observation of the microstructure of 7075 aluminum alloy by TEM indicates that positive and negative alternating electrical impulse aging heat treatment can multiply the number and improve the dispersion degree of precipitate η′ compared with conventional aging heat treatment; grain boundary precipitate transforms from small continuous distribution to coarsening discontinuous distribution. As a result, the positive and negative alternating electrical impulse aging heat treatment is better than conventional aging heat treatment on the aluminum alloy in improving the microstructure and properties.
Key words: 7075 aluminum alloy; positive and negative alternating electrical impulse; aging heat treatment; mechanical properties; microstructure
