AA 7055鋁合金時效析出過程的小角度X射線散射定量表征

AA 7055鋁合金時效析出過程的小角度X射線散射定量表征QUANTITATIVE CHARACTERIZATION ON THE PRECIPITATION OF AA 7055 ALUMINUM ALLOY BY SAXS

利用小角度X射線散射（SAXS）技術(shù)系統(tǒng)、定量地研究了AA 7055鋁合金在120和160℃時效過程中析出相的演變規(guī)律。結(jié)果表明，在120℃時效時，隨時效時間延長析出相半徑不斷增加，時效5h后半徑基本穩(wěn)定，約為3.3nm，且尺寸分布基本不變；析出相的體積分?jǐn)?shù)隨著時效時間的延長不斷增加，由時效5h時的2.4%增加到時效60h時的5.2%。在160℃時效時，隨時效時間延長析出相半徑不斷增加，由時效0.5h時的3.1nm增加到時效72h時的11.7nm，尺寸分布范圍也隨著時效時間的延長而逐漸增加；析出相的體積分?jǐn)?shù)隨著時效時間的延長先不斷增加，由時效0.5h時的1.4%增加到時效16h時的5.4%，時效16h后趨于平衡。在120和160℃時效時，析出相均屬于軸比介于0.2~0.3之間的扁橢球狀，即為盤狀。

The evolution of the precipitates during ageing at 120 and 160oC in AA 7055 aluminum alloy were investigated systematically and quantitatively by small angle X-ray scattering (SAXS) technique. The results show that, when ageing at 120oC, the average radius of the precipitates increases with increasing the ageing time. After ageing for 5h and later, the average radius of the precipitates is 3.3 nm, and its distribution almost keeps stably. The volume fraction of the precipitates is also increased with increasing the ageing time. When ageing from 5h to 60h, the volume fraction increases from 2.4% to 5.2%. When ageing at 160oC, however, the average radius of the precipitates increases from 3.1nm to 11.7nm with increasing the ageing time from 0.5h to 72h. The volume fraction of the precipitates increases from 1.4% to 5.4% with increasing the ageing time from 0.5h to 16h. After ageing for 16h and later, the volume fraction of the precipitates keeps stably. Both ageing at 120 and 160oC, the morphology of the precipitates is similar to a flat ellipsoid with an axis ratio between 0.2 and 0.3. Based on these quantitative results of the precipitates, the strength models during ageing will be built possibility.

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