亚共晶Al-Si合金中微量元素La变质共晶Si的关键影响因素  

Key Factors Influencing Eutectic Si Modification in Al-Si Hypoeutectic Alloy by Trace La

作　　者：张丽丽[1] 吉宗威 赵九洲[1] 何杰[1] 江鸿翔[1] ZHANG Lili;JI Zongwei;ZHAO Jiuzhou;HE Jie;JIANG Hongxiang(Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]中国科学院金属研究所师昌绪先进材料创新中心,沈阳110016 [2]南方科技大学材料科学与工程学院,深圳518055

出　　处：《金属学报》2023年第11期1541-1546,共6页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2021YFA0716303;中国载人空间站项目;国家自然科学基金项目Nos.51901231和51971227。

摘　　要：理论分析了亚共晶Al-Si合金中微量元素La变质共晶Si的关键影响因素。结果表明,La在α-Al中最大固溶度及La与Al、Si的相互作用参数决定其对共晶Si的变质效果。当La的添加量低于其在α-Al中最大固溶度时,La分布在α-Al和共晶Si中,其变质效果随着La添加量的增加而增加。当La的添加量大于其在α-Al中最大固溶度时,由于La与Al、Si的相互作用参数较大且2者相近,会形成含Al、Si、La的三元化合物,计算结果表明,在各种可能Al、Si、La的化合物中,AlSiLa的形成热较大,且与Al熔体间的界面能较低,最易在熔体中形成;此时,La分布在α-Al、AlSiLa和共晶Si中,其中La在α-Al和共晶Si中的浓度基本不随La添加量的增加而变化,变质效果亦基本保持不变。当变质元素的添加量接近其在α-Al中的最大固溶度时,变质效果最佳。The modification of eutectic Si to fiber morphology from coarse plate-like morphology is essential for producing an Al-Si hypoeutectic alloy.Furthermore,chemical modification through the addition of modifying elements,such as Na and Sr,to melt is the most widely used method in industrial production to improve microstructures.Recently,the effect of rare earth metals on the eutectic Si modification has also attracted considerable attention,especially for the economical element La.Key factors influencing eutectic Si modification in Al-Si hypoeutectic alloy by trace La are theoretically explored.The results demonstrate that the solubility of La in the primaryα-Al phase and interaction parameter between La and Al(or Si)primarily contribute to the eutectic Si modification.When the addition level of trace La is within its solubility in the primaryα-Al phase,La distributes inα-Al and eutectic Si,and the modification effect increases with the La addition level.When the addition level of trace La is greater than its solubility inα-Al,a ternary compound containing Al,Si,and La exists before the eutectic reaction due to the significant value of the interaction parameter between La and Al(or Si).Calculated results further prove that the composition of the ternary compound is AlSiLa due to the substantial value of heat for the formation of AlSiLa and the small value of interfacial energy between Al melt and AlSiLa.Under this condition,La distributes inα-Al,AlSiLa,and eutectic Si,and the La content inα-Al and eutectic Si almost remain constant.Thus,the modification effect almost stays unchanged with La addition.A suitable modification effect is achieved when the La addition level is around its solubility in the primaryα-Al phase.

关 键 词：亚共晶AL-SI合金 变质 相互作用参数 微量元素La 固溶度 

分 类 号：TG111.4[金属学及工艺—物理冶金]