冷速与稀土协同作用对Al-Sc合金组织及硬度的影响  

Effects of Synergy Rale of Cooling Rate and RE Content on Structure and Hardness of Al-Sc Alloy

作　　者：吴宗锴 杨伟 刘灵 张丽攀 余欢 Wu Zongkai;Yang Wei;Liu Ling;Zhang Lipan;Yu Huan(National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology,Nanchang Hangkong University)

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,南昌330063

出　　处：《特种铸造及有色合金》2022年第10期1291-1295,共5页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(52061032,51461032);江西省教育厅资助项目(GJJ180513)。

摘　　要：采用真空感应熔炼和铜模喷铸相结合,研究了不同冷速及稀土含量对Al-Sc合金凝固组织及硬度的影响。结果发现,随Sc含量增加,铸态Al-Sc合金的等轴晶组织发生细化,其中过共晶Al-0.8Sc合金的细化效果最佳,平均晶粒尺寸仅为106μm,相比未添加Sc的纯Al下降了97.6%。由于铜模喷铸的强激冷效果,快冷Al-Sc合金的非平衡凝固组织表现为择优生长的细长柱状晶。加入稀土Sc后发生典型的柱状晶向等轴晶转变,且中心等轴晶比例随Sc含量增加而不断扩大。冷速的提高抑制了初生AlSc相的形成,有利于获得过饱和固溶体,但析出强化效应的减弱导致快冷合金显微硬度相比铸态合金有所下降。The influence of cooling rate and RE content on microstructure and hardness of Al-Sc alloy was investigated by the combination of vacuum induction melting and spray casting. The results indicate that the equiaxed crystal structure in as-cast alloy is gradually refined with the increase of Sc content, and desirable refinement effect can be obtained in Al-0.8 Sc hypereutectic alloy with the average grain size of 106 μm, which is reduced by 97.6% in comparison with that of pure Al. Due to the strong chilling effect of copper mould injection, non-equilibrium solidification microstructure of the fast-cooling Al-Sc alloy is characterized by preferentially grown columnar crystals, which is typically transformed to equiaxed grain after Sc addition, and the ratio of latter is enlarged as the Sc content increases. The increase of cooling rate inhibits the formation of primary AlSc phase, which is favorable to supersaturated solid solution. However, the weakening of precipitation strengthening effect results in a lower microhardness of the fast-cooling alloy than that of the as-cast alloy.

关 键 词：非平衡凝固 异质形核 晶粒细化 稀土铝 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG113[金属学及工艺—金属材料]