高Zn含量Al-Zn-Mg-Cu-Zr合金中添加微量Sc后的晶粒细化及显微特征

• 作 者: 温凯 李锡武 熊柏青 刘洪雷 王英君 李志辉 张永安 李亚楠
• 出 处: 中南大学学报（英文版）
• 发表日期: 2022年3期
• 关键词: Al-Zn-Mg-Cu-Zr alloy high zinc content microstructure Sc addition grain refineme

本文在一种高Zn含量Al-9.2Zn-2.0Mg-1.0Cu-0.11Zr合金中添加一系列的微量Sc元素(0.06 wt.％,0.10 wt.％,0.14 wt.％,0.17 wt.％,0.20 wt.％和0.25 wt.％),研究了包含晶粒及第二相在内的铸态组织特征.结果表明,组织中出现细晶界,MgZn2相在该晶界上不连续分布.此外,发现了AlZnMgCu共晶相和具有絮状形貌的含Sc、Zr相.当Sc元素含量从0.06 wt.％增加到0.17 wt.％时,平均晶粒尺寸持续降低,晶粒趋于等轴.同时,AlZnMgCu共晶相含量呈降低趋势.当Sc元素含量为0.20 wt.％和0.25 wt.％时,没有发现更进一步的晶粒细化效果,且AlZnMgCu共晶相含量不再降低.此外,组织中出现具有块状形貌的含Sc、Zr相,且Sc元素含量为0.25 wt.％的合金中块状含Sc、Zr相的数量多于Sc元素含量为0.20 wt.％的合金.本文进一步讨论了添加Sc元素对细化晶粒及AlZnMgCu共晶相含量减少的影响.“,”In the present work, scandium elements with a series of contents (0.06 wt.％, 0.10 wt.％, 0.14 wt.％, 0.17 wt.％, 0.20 wt.％and 0.25 wt.％) were added in a high Zn-containing Al-Zn-Mg-Cu-Zr alloy and the corresponding as-cast microstructure characteristics including grains and phases were thoroughly investigated. The results indicated that fine grain boundaries existed in these alloys and fine MgZn2 phases discontinuously distributed on them. Besides, AlZnMgCu eutectic phases and Sc, Zr-containing phases with flocculent morphology were observed. As scandium contents vary from 0.06 wt.％ to 0.17 wt.％ , the average grain size continuously decreased and its equiaxial characteristics were strengthened. Meanwhile, the content of AlZnMgCu eutectic phase showed a decrease trend. When scandium contents were 0.20 wt.％and 0.25 wt.％, no further enhancement on grain refinement was observed, so as to the reduction of AlZnMgCu eutectic phase content. Besides, Sc, Zr-containing phases with blocky morphology were observed and the alloy with a scandium content of 0.25 wt.％ possessed a larger amount of blocky Sc, Zr-containing phase than the alloy with a scandium content of 0.20 wt.％. Grain refinement and reduction of AlZnMgCu eutectic phase content associated with scandium addition were discussed.