(北京有色金屬研究總院 有色金屬材料制備加工國家重點(diǎn)實(shí)驗(yàn)室，北京100088)
摘 要: 采用溫度數(shù)據(jù)采集系統(tǒng)采集得到鹽浴爐等溫保溫過程中試樣的溫度變化曲線，通過硬度和電導(dǎo)率測試測定7050鋁合金的時(shí)間－溫度－性能(TTP)曲線。采用透射電鏡和熱分析儀對(duì)7050鋁合金進(jìn)行顯微組織觀察和分析。結(jié)果表明：合金TTP曲線鼻溫大約在320 ℃，孕育期約為1.7 s。合金的淬火敏感溫度區(qū)間為230~410 ℃，且在此溫度區(qū)間內(nèi)，合金硬度隨時(shí)間的延長而迅速下降。等溫保溫過程中，合金晶內(nèi)淬火平衡η相主要依附于晶內(nèi)Al3Zr等彌散相和細(xì)小Al2Cu相形核長大；且隨著保溫時(shí)間延長，淬火析出相的體積分?jǐn)?shù)逐漸增加，晶界析出相趨向于連續(xù)分布，無析出帶逐漸寬化。等溫保溫合金經(jīng)時(shí)效后，晶內(nèi)析出GPⅡ區(qū)及η׳相數(shù)量隨著等溫保溫時(shí)間的延長逐漸減少，使得合金性能降低，合金表現(xiàn)出一定淬火敏感性。
關(guān)鍵字: 淬火特性；TTP曲線；淬火敏感性；形核核心；時(shí)效析出相
（State Key Laboratory of Nonferrous Metals and Processes,
General Research Institute for Nonferrous Metals，Beijing 100088, China）
Abstract:The time-temperature-property (TTP) curve of aluminum alloy 7050 was determined and the microstructure of the alloy under different processing was investigated. The results indicate that the nose temperature and incubation period of TTP curves is about 320 ℃, 1.7 s, respectively and the quench sensitive temperature range of TTP curve for 7050 alloy is 230−410 ℃. The volume of the coarse equilibrium η phases that precipitated at grain boundaries and in the grains during isothermal-holding increases with the isothermal-holding time, which results in the decrease of subsequent aging hardening precipitates(GPII zones and η׳ phases) for loss of solutes and vacancies. The grain boundary precipitates tend to distribute continuously with wider precipitation free zone. The primary nuclear sites for coarse equilibrium η phases are Al3Zr despersoids and Al2Cu particles in the grains.
Key words: hardenability characteristic; TTP curve; quench sensitivity; nuclear site; ageing precipitate
