(湖南大學(xué)材料科學(xué)與工程學(xué)院，長沙 410082)
摘 要: 采用熱電力(TEP)、掃描電鏡(SEM)和透射電鏡(TEM)等顯微表征技術(shù)，結(jié)合硬度和韌性測試，研究中斷時(shí)效工藝(IA)對S相為主要強(qiáng)化相的AA2024鋁合金的力學(xué)性能和顯微結(jié)構(gòu)的影響。合金經(jīng)180℃欠時(shí)效處理后，分別在室溫和65℃進(jìn)行低溫時(shí)效處理即中斷時(shí)效(T6I4)，然后在180℃進(jìn)行再時(shí)效處理(T6I6)。結(jié)果表明：相比T6工藝，T6I4工藝處理的合金可以獲得較好的韌性，但硬度略有降低；而T6I6工藝會(huì)同時(shí)降低合金的韌性和硬度。低溫中斷時(shí)效處理時(shí)，欠時(shí)效過程形成的S相基本不發(fā)生變化，合金內(nèi)部形成的原子團(tuán)簇可能是T6I4狀態(tài)韌性提高的原因。T6I6再時(shí)效過程中沒有形成更多的S相，且原有的S相明顯粗化，T6I6峰值時(shí)效狀態(tài)下，合金力學(xué)性能變差；AA2024合金中斷時(shí)效過程中沒有析出能夠形成S相的形核點(diǎn)。
關(guān)鍵字: AA2024合金；析出；中斷時(shí)效處理；硬度；韌性
（College of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The effect of interrupted ageing(IA) on the mechanical property and microstructure of AA2024 alloy, in which the S phase serves as the main strengthening phase, was investigated by the thermal electrical power (TEP),scanning electron microscopy (SEM), transmission electron microscopy(TEM) and hardness and toughness tests. The interrupted ageing at room temperature or 65℃was implemented on samples under-aged at 180℃ for T6I4 treatment, then re-ageing at 180℃ for T6I6 treatment. The results show that the T6I4 treatment can render better toughness and slightly lower the hardness of AA2024 alloy compared with T6 temper, presumably because of atomic clusters form during IA. Unfortunately, both hardness and toughness are worse after T6I6 treatments, under which, no precipitation of additional S phase but coarsening ones can be observed. It is thus reasonable to conclude that the low-temperature IA is not favorable to produce more Sphase nucleus which can grow further during re-ageing.
Key words: AA2024 alloy; precipitation; interrupted ageing; hardness; toughness
