微觀組織與性能的影響
(1. 西南鋁業(yè)(集團)有限責任公司技術中心, 重慶 401326)
(2. 中南大學 材料科學與工程學院， 長沙 410083)
摘 要: 通過合金室溫力學性能測試及時效組織的透射電鏡分析，研究了分級時效對Al-Cu-Li-Mg-Mn-Zr合金顯微組織與性能的影響。結果表明， 經過先低溫后高溫的三級時效可使合金獲得比T6處理更高的強度, 且隨著第二級時效時間的延長， 合金抗拉強度和屈服強度逐漸提高。采用先高溫后低溫二級時效，可獲得較先低溫后高溫三級時效更高的力學性能， 且其強度隨第一級高溫時效時間的延長而增加， 達到T8峰時效的強度水平。合金在先低溫后高溫時效時，在100 ℃低溫預時效形成GP區(qū)， 在140 ℃析出彌散細小的δ′、θ′和T1相并穩(wěn)定下來， 然后在175 ℃進一步析出長大， 從而提高了合金強度。當合金在先高溫后低溫二次時效時，高溫欠時效析出δ′和T1等強化相，然后在140 ℃較低溫度二次析出大量細小彌散的δ′相，產生二次強化效果。
關鍵字: 鋁鋰合金; 時效; 微觀結構；力學性能
Al-Cu-Li-Mg-Mn-Zr alloys
（ 1. Technology Centre, Southwest Aluminum Industry Ltd.Co.,
Chongqing 401326, China;
(2. School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The effects of multi-stage ageing treatments on the microstructure and mechanical properties of Al-Cu-Li-Mg-Mn-Zr alloy were investigated．Compared with T6 treatment, higher mechanical properties can be obtained by multi-stage ageing treatments， especially the treatment of (175 ℃, 24 h)+(140 ℃, 36 h) leads to an excellent combination of strength and ductility. When the alloy is pre-aged at lower temperature(100 ℃), the GP zone is preferentially precipitated, and the fine and dispersed δ′, θ′ and T1 phases are precipitated at 140 ℃. These precipitates continue to grow at 175 ℃, which improves the strength of alloy. The combined effects of δ′, θ′ and T1 precipitates at the first age stage of 175 ℃ and the secondary-precipitation at the second stage of 140 ℃ can be aroused, which results in higher strength(close to that in T8 treatment) than that of the alloy pre-aged at lower temperature then at elevated temperature.
Key words: Al-Li alloy; ageing; microstructure; mechanical property
