(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
2. 湖南城市學(xué)院 土木工程學(xué)院，益陽(yáng) 413000)
摘 要: 采用透射電鏡分析、力學(xué)拉伸性能測(cè)試和電導(dǎo)率測(cè)試， 研究不同回歸再時(shí)效（RRA）處理制度對(duì)含Sc超高強(qiáng)Al-Zn-Mg-Cu-Zr合金組織與性能的影響。結(jié)果表明：采用120 ℃，24 h預(yù)時(shí)效+180 ℃，30 min回歸處理+120 ℃，24 h終時(shí)效的RRA處理工藝，可以使合金獲得理想的力學(xué)性能和抗應(yīng)力腐蝕性能；與T6態(tài)相比，該工藝獲得的合金強(qiáng)度僅略微下降，而電導(dǎo)率則大大提高；含Sc超高強(qiáng)Al-Zn-Mg-Cu-Zr合金經(jīng)RRA處理后，晶內(nèi)含大量均勻細(xì)小的η′相和少量的η平衡相，合金晶界處的平衡相粗化明顯，呈現(xiàn)斷續(xù)、孤立分布；與T6態(tài)處理的合金相比，無(wú)沉淀析出帶變寬；其晶內(nèi)析出相與T6峰值時(shí)效態(tài)的類似，晶界組織與雙級(jí)過(guò)時(shí)效態(tài)的組織類似。
關(guān)鍵字: Al-Zn-Mg-Cu-Zr合金；Sc；超高強(qiáng)；再時(shí)效；力學(xué)性能；微觀組織
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Department of Civil Engineering, Hunan City University, Yiyang 413000, China）
Abstract:The effects of retrogression and reaging (RRA) treatment on the microstructures and mechanical properties of super-high strength Al-Zn-Mg-Cu-Zr alloy containing Sc were studied by transmission electron microscopy, tensile and conductivity tests. The results show that perfect mechanical and stress corrosion resistance properties can be gained if the alloy is treated by the RRA heat treatment of 120 ℃, 24 h pre-ageing, 180℃, 30 min retrogression and 120℃, 24 h re-ageing. Compared with the T6 sample, the strength of the alloy decreases slightly while the conductivity increases greatly. Treated by RRA, a great amount of fine and homogenized distributed precipitations η′ and few equilibrium phases η are observed inside the grains, while the equilibrium phases on the grain boundaries coarsen obviously, distributing discontinuously and isolated. The precipitation free zones are broadened than that of the T6 sample. The microstructure inside the grains is similar to that of the T6 sample while the microstructure of the grain boundary is similar to that of the duplex over-aged sample.
Key words: Al-Zn-Mg-Cu-Zr alloy; Sc; super-high strength; re-aging; mechanical properties; microstructure
