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時(shí)效過程中亞晶界析出演變對(duì)7050鋁合金性能的影響
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更新時(shí)間：2015-09-16
采用光學(xué)顯微鏡、電子背散射衍射和透射電鏡，研究亞晶界析出演變對(duì)7050鋁合金時(shí)效過程電導(dǎo)率和沖擊韌性的影響。
時(shí)效過程中亞晶界析出演變對(duì)7050鋁合金性能的影響Effect of precipitation evolution at sub-grain boundary on properties of 7050 Al alloy during aging
采用光學(xué)顯微鏡、電子背散射衍射和透射電鏡，研究亞晶界析出演變對(duì)7050鋁合金時(shí)效過程電導(dǎo)率和沖擊韌性的影響。結(jié)果表明：亞晶界上析出相轉(zhuǎn)變后，在二級(jí)時(shí)效過程中完成長(zhǎng)大過程，并使電導(dǎo)率升高，沖擊韌性降低。時(shí)效過程中亞晶界取向差增大，有利于η′相在亞晶界形核。一級(jí)時(shí)效升溫至二級(jí)時(shí)效使亞晶界η′相轉(zhuǎn)變?yōu)棣窍?，且電?dǎo)率升高13.04%，沖擊韌性降低53.91%。二級(jí)時(shí)效過程中，亞晶界η相持續(xù)轉(zhuǎn)變長(zhǎng)大、無析出自由區(qū)寬化以及晶內(nèi)析出量增加，導(dǎo)致電導(dǎo)率升高，沖擊韌性降低。統(tǒng)計(jì)Graff試劑侵蝕金相中的晶界長(zhǎng)度演變確定亞晶界η相的轉(zhuǎn)變長(zhǎng)大完成過程為(121 ℃, 360 min)+(177 ℃, 60 min)。
The effects of precipitation evolution at sub-grain boundaries on electrical conductivity and impact toughness of 7050 aluminum alloy during aging were investigated by optical microscopy, electron back scatter diffraction and transmission electron microscopy. The results show that the electrical conductivity increases and the impact energy drops due to the transformation and growth of precipitation. η′ phase prefers to precipitate at sub-grain boundaries as the misorientation increases. At the heating stage between two-step aging, the electrical conductivity rises by 13.04% and impact toughness decreases by 53.91% as transformation from η′ to η. The microstructure evolutions including η phase precipitating at sub-grain boundaries, precipitate spacing increasing and precipitation-free-zone widening improve the electrical conductivity but deteriorate the impact toughness. The length of grain boundaries etched by Graff solution and viewed in the optical microscopy was counted to ensure the transformation and growth of η phase completed at (121 ℃, 360 min)+(177 ℃, 60 min).
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