CAJ | 학술논문

采用光学显微镜、电子背散射衍射和透射电镜,研究亚晶界析出演变对 7050 铝合金时效过程电导率和冲击韧性的影响.结果表明:亚晶界上析出相转变后,在二级时效过程中完成长大过程,并使电导率升高,冲击韧性降低.时效过程中亚晶界取向差增大,有利于η′相在亚晶界形核.一级时效升温至二级时效使亚晶界η′相转变为η相,且电导率升高13.04%,冲击韧性降低53.91%.二级时效过程中,亚晶界η相持续转变长大、无析出自由区宽化以及晶内析出量增加,导致电导率升高,冲击韧性降低.统计 Graff 试剂侵蚀金相中的晶界长度演变确定亚晶界η相的转变长大完成过程为(121℃, 360 min)+(177℃, 60 min).
채용광학현미경、전자배산사연사화투사전경,연구아정계석출연변대 7050 려합금시효과정전도솔화충격인성적영향.결과표명:아정계상석출상전변후,재이급시효과정중완성장대과정,병사전도솔승고,충격인성강저.시효과정중아정계취향차증대,유리우η′상재아정계형핵.일급시효승온지이급시효사아정계η′상전변위η상,차전도솔승고13.04%,충격인성강저53.91%.이급시효과정중,아정계η상지속전변장대、무석출자유구관화이급정내석출량증가,도치전도솔승고,충격인성강저.통계 Graff 시제침식금상중적정계장도연변학정아정계η상적전변장대완성과정위(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 fromη′ toη. The microstructure evolutions includingη 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 ofηphase completed at (121℃, 360 min)+(177℃, 60 min).