工程科学学报,第38卷,第2期:263-269,2016年2月 Chinese Journal of Engineering,Vol.38,No.2:263-269,February 2016 DOI:10.13374/j.issn2095-9389.2016.02.016:http://journals.ustb.edu.cn 蛇形通道制备半固态A380铝合金浆料组织的演变 刘志勇,毛卫民四,王伟番,郑志凯 北京科技大学材料科学与工程学院,北京100083 ☒通信作者,E-mail:weiminmao@263.net 摘要采用石墨质蛇形通道制备半固态A380铝合金浆料,并研究浆料制备过程中浆料组织的演变.结果显示,合金熔体 在蛇形通道内发生一次凝固,在其通道内壁的激冷和异质形核作用下形成大量的初生自由晶,半固态浆料的剩余液相在收集 坩埚内发生二次凝固形成二次非枝晶。初生晶粒的游离模型表明一部分初生自由晶直接生长为球晶,其他部分则成长为枝 晶,枝晶在“自搅拌”的作用下发生缩颈和熔断,通过“自旋转”在蛇形通道内得到初步球化和熟化.二次凝固形成的二次非枝 晶在收集坩埚内得到初步球化和熟化,同时初生晶粒在收集坩埚内得到进一步球化、熟化和均匀分布 关键词铝合金:半固态浆料:蛇形通道;组织演变:游离 分类号TG249:TG146.21 Microstructure evolution of the A380 aluminum alloy semi-solid slurry prepared by serpentine channel LIU Zhi-yong,MAO Wei-min,WANG Wei-pan,ZHENG Zhi-kai School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:weiminmao@263.net ABSTRACT The semi-solid slurry of A380 aluminum alloy was prepared by using a graphite serpentine channel and the microstruc- ture evolution during solidification was investigated.The result showed that,initial solidification occurred in the serpentine channel, and a large number of primary free grains generated in the alloy melt under the influence of chilling and heterogeneous nucleation caused by the serpentine channel inner wall.Secondary non-dendrites formed during secondary solidification which occurred in the remaining alloy melt of the semi-solid slurry in the collective crucible.The drifting model of primary grains displayed that a part of primary free grains directly grew to spherical grains,and others developed to dendrites.The "self-stirring"of the alloy melt made dendrites neck and fuse,and they got initial spheroidization and ripening through the "self-rotating"in the serpentine channel. Secondary non-dendrites formed during secondary solidification got initial spheroidization and ripening in the collective crucible.Mean- while,the primary grains got further spheroidization,ripening and uniform distribution in the collective crucible. KEY WORDS aluminum alloys;semi-solid slurry:serpentine channels;microstructural evolution:drifting l972年Spencer等m提出半固态成形技术,即触 对流的方法,如机械搅拌R-习和电磁搅拌,Spencer 变成形和流变成形,其中流变成形具有高效率、低能和Flemings等-认为非枝晶组织来源于枝晶的机 耗和品质优等特点,因此得到广泛关注和研究.制备 械折断、破碎、磨圆以及枝晶熟化引起的根部熔断, 半固态浆料是流变成形的关键,而半固态浆料中初即枝晶折断破碎理论和枝晶熔断理论.Fa等则 生晶粒的形貌和分布情况决定其品质.针对如何制 认为搅拌引起的强制对流有利于提高形核率从而抑 备高品质半固态浆料,早期研究者采用强剪切和强 制枝晶的生长,即抑制枝晶生长理论.李涛等切认为 收稿日期:2014-12-16 基金项目:国家重点基础研究发展计划资助项目(2011CB606300):国家自然科学基金资助项目(50774007)工程科学学报,第 38 卷,第 2 期: 263--269,2016 年 2 月 Chinese Journal of Engineering,Vol. 38,No. 2: 263--269,February 2016 DOI: 10. 13374 /j. issn2095--9389. 2016. 02. 016; http: / /journals. ustb. edu. cn 蛇形通道制备半固态 A380 铝合金浆料组织的演变 刘志勇,毛卫民,王伟番,郑志凯 北京科技大学材料科学与工程学院,北京 100083 通信作者,E-mail: weiminmao@ 263. net 摘 要 采用石墨质蛇形通道制备半固态 A380 铝合金浆料,并研究浆料制备过程中浆料组织的演变. 结果显示,合金熔体 在蛇形通道内发生一次凝固,在其通道内壁的激冷和异质形核作用下形成大量的初生自由晶,半固态浆料的剩余液相在收集 坩埚内发生二次凝固形成二次非枝晶. 初生晶粒的游离模型表明一部分初生自由晶直接生长为球晶,其他部分则成长为枝 晶,枝晶在“自搅拌”的作用下发生缩颈和熔断,通过“自旋转”在蛇形通道内得到初步球化和熟化. 二次凝固形成的二次非枝 晶在收集坩埚内得到初步球化和熟化,同时初生晶粒在收集坩埚内得到进一步球化、熟化和均匀分布. 关键词 铝合金; 半固态浆料; 蛇形通道; 组织演变; 游离 分类号 TG249; TG146. 21 Microstructure evolution of the A380 aluminum alloy semi-solid slurry prepared by serpentine channel LIU Zhi-yong,MAO Wei-min ,WANG Wei-pan,ZHENG Zhi-kai School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail: weiminmao@ 263. net ABSTRACT The semi-solid slurry of A380 aluminum alloy was prepared by using a graphite serpentine channel and the microstructure evolution during solidification was investigated. The result showed that,initial solidification occurred in the serpentine channel, and a large number of primary free grains generated in the alloy melt under the influence of chilling and heterogeneous nucleation caused by the serpentine channel inner wall. Secondary non-dendrites formed during secondary solidification which occurred in the remaining alloy melt of the semi-solid slurry in the collective crucible. The drifting model of primary grains displayed that a part of primary free grains directly grew to spherical grains,and others developed to dendrites. The“self-stirring”of the alloy melt made dendrites neck and fuse,and they got initial spheroidization and ripening through the “self-rotating”in the serpentine channel. Secondary non-dendrites formed during secondary solidification got initial spheroidization and ripening in the collective crucible. Meanwhile,the primary grains got further spheroidization,ripening and uniform distribution in the collective crucible. KEY WORDS aluminum alloys; semi-solid slurry; serpentine channels; microstructural evolution; drifting 收稿日期: 2014--12--16 基金项目: 国家重点基础研究发展计划资助项目( 2011CB606300) ; 国家自然科学基金资助项目( 50774007) 1972 年 Spencer 等[1]提出半固态成形技术,即触 变成形和流变成形,其中流变成形具有高效率、低能 耗和品质优等特点,因此得到广泛关注和研究. 制备 半固态浆料是流变成形的关键,而半固态浆料中初 生晶粒的形貌和分布情况决定其品质. 针对如何制 备高品质半固态浆料,早期研究者采用强剪切和强 对流的方法,如机械搅拌[2--3]和电磁搅拌[4--5],Spencer 和 Flemings 等[1--2]认为非枝晶组织来源于枝晶的机 械折断、破碎、磨圆以及枝晶熟化引起的根部熔断, 即枝晶折断破碎理论和枝晶熔断理论. Fan 等[6]则 认为搅拌引起的强制对流有利于提高形核率从而抑 制枝晶的生长,即抑制枝晶生长理论. 李涛等[7]认为