微量Sc對7085鋁合金淬火敏感性的影響Effect of minor Sc on quench sensitivity of 7085 aluminum alloy

采用末端淬火實驗、光學顯微鏡、差熱分析、能譜儀和透射電鏡研究微量Sc對7085鋁合金淬火敏感性的影響。結果表明：在7085鋁合金中添加Sc會提高該合金的淬火敏感性。添加Sc后，會在基體中形成彌散分布的Al₃(Sc, Zr)粒子，該粒子能夠穩定亞晶，強烈抑制再結晶，增加晶界數量；在淬火過程中，隨著冷卻速度的降低，粗大的平衡η相以Al₃(Sc，Zr)粒子為異質形核核心析出，同時也在亞晶界上大量析出長大；η相的析出，降低了基體固溶體的過飽和度，提高了合金的淬火敏感性。

The effect of minor Sc on quench sensitivity of 7085 aluminum alloy was investigated by an end-quenching test method, optical microscopy(OM), differential scanning calorimetry(DSC), energy distribution spectrum(EDS) and transmission electron microscopy(TEM). The results show that minor Sc can enhance the quench sensitivity of 7085 aluminum alloy. The Al₃(Sc, Zr) particles form and disperse in grain uniformly, and stabilize the subgrains, inhibite the recrystallization of the alloy strongly and increase the amount of grain boundaries. As the quenching rate decreases, however, the equilibrium MgZn₂?(η) precipitates nucleate heterogeneously on Al₃(Sc, Zr) dispersoids and precipitate on subgrain boundaries. The precipitation of η phase reduces the solutes available for aging hardening, leading to the increase of the quench sensitivity of this alloy.

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