鋁鋰合金熱機械處理研究進展

鋁鋰合金熱機械處理研究進展Research and Progress of Thermomechanical Treatment of Al-Li Alloys

綜述了熱機械處理對新型鋁鋰合金強韌化機制影響的研究,深入分析討論了熱機械處理對鋁鋰合金晶粒結(jié)構(gòu)和沉淀相等顯微組織演變規(guī)律的影響。通過熱機械處理改變主要沉淀相的析出順序和析出行為,促進基體形成細小、彌散和均勻分布的以δ',θ"/θ',T1,S"S'相為主的聯(lián)合強化組織,抑制晶界沉淀相的析出和長大以及晶界無析出帶的寬化,能夠顯著改善鋁鋰合金的強度和塑韌性匹配。經(jīng)過固溶處理基體溶質(zhì)原子和空位密度顯著上升,淬火后形成這些缺陷過飽和固溶體為隨后時效析出提供了動力。預(yù)變形和預(yù)時效促進了基體細小彌散的沉淀相δ'相或G.P.區(qū)均勻形核析出,在高溫時效調(diào)節(jié)和穩(wěn)定沉淀相尺寸和體積分數(shù),獲得T1、θ"/θ'和δ'相混合組織。新型和特殊熱機械處理調(diào)控主要強化相δ',θ"/θ',T1相析出比例、尺寸和取向,細化晶粒和優(yōu)化晶粒結(jié)構(gòu)。最后指出應(yīng)開發(fā)大規(guī)格軋制板材和熱鍛件的應(yīng)力時效等新型熱機械處理工藝,以滿足大型航空飛機和重型運載火箭對輕質(zhì)高性能鋁鋰合金需求。

The strengthening and toughening mechanism of aluminum lithium alloy treated by thermo-mechanical processing have been summarized, and the effect on the evolution of microstructures, grain structure and precipitation, were discussed and analysed deeply. The precipitation sequence and behavior of the main precipitation phase were modified by the thermo-mechanical processing, stimulating the forming of fine dispersion combined particles of δ',θ"/θ', T1, and S"/S' phases, uniformly distributed in the matrix, which significantly improved the relationships of strength and the plastic toughness, with the inhibiting of broadening of precipitate free zones, and of the precipitation and coarsening of strengthening particles at the grain boundary.The density of solute atom and vacancies significantly raised up after solution treating, and retained as supersaturated solid solution after water quenching, which acted as the driving force for the precipitation during subsequent aging. Pre-deformation and pre-aging significantly increased the density of fine dispersion strengthening particles of δ' and G.P. zones,which uniformly nucleated in the matrix, and the combined strengthening phases of δ',θ"/θ', and T1 were obtained after high temperature second aging, controlling the size and volume fraction of these particles.Refined grain and optimal grain structure were achieved by new and typical thermo-mechanical processing, and the proportion, size, and oriented relationship of main strengthening particles of δ',θ"/θ', and T1 phases were optimized.At last, the research direction of new thermo-mechanical treatment on the large scale rolled plates and hot worked forgings is pointed out, such as age forming, to meet the need of light high performance of new aluminum lithium alloys used for the large aircrafs and heavy lift launch vehicles.

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