Understanding grain refining and anti Si-poisoning effect in Al-10Si/Al-5Nb-B system
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2021年第6期
论文作者：Yang Li Ying Jiang Bin Liu Qun Luo Bin Hu Qian Li
摘 要：Grain refinement is critical for fabricating high-quality Al-Si casting components in the application of automobile and aerospace industries,while the well-known Si-poisoning effect makes it difficult.Nbbased refiners offer an effective method to refine Al-Si casting alloys,but their anti Si-poisoning capability is far from being understood.In this work,the grain refining mechanism and the anti Si-poisoning effect in the Al-10 Si/Al-5 Nb-B system were systematically investigated by combining transmission electron microscope,first-principles calculations,and thermodynamic calculations.It is revealed that NbB2 provides the main nucleation site in the Al-10 Si ingot inoculated by 0.1 wt.%Nb Al-5 Nb-B refiner.The exposed Nb atoms on the（0 0 0 1） NbB2 and（1-100） NbB2 surface can be substituted by Al to form（Al,Nb）B2 intermedia layers.In addition,a layer of NbAl3-like compound（NbAl3 ’） can cover the surface of NbB2 with the orientation relation of（1-100）[1 1-2 0] NbB2//（110）[110]NbAl3 ’.Both of the（Al,Nb）B2 and NbAl3’intermedia layers contribute to enhancing the nucleation potency of NbB2 particles.These discoveries provide fundamental insight to the grain refining mechanism of the Nb-B based refiners for Al-Si casting alloys and are expected to guide the future development of stronger refiners for Al-Si casting alloys.
Yang Li1，Ying Jiang1，Bin Liu1，Qun Luo1，Bin Hu2，Qian Li1
1. Materials Genome Institute, State Key Laboratory of Advanced Special Steels, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University2. China Science Lab, General Motors Global Research and Development
摘 要：Grain refinement is critical for fabricating high-quality Al-Si casting components in the application of automobile and aerospace industries,while the well-known Si-poisoning effect makes it difficult.Nbbased refiners offer an effective method to refine Al-Si casting alloys,but their anti Si-poisoning capability is far from being understood.In this work,the grain refining mechanism and the anti Si-poisoning effect in the Al-10 Si/Al-5 Nb-B system were systematically investigated by combining transmission electron microscope,first-principles calculations,and thermodynamic calculations.It is revealed that NbB2 provides the main nucleation site in the Al-10 Si ingot inoculated by 0.1 wt.%Nb Al-5 Nb-B refiner.The exposed Nb atoms on the（0 0 0 1） NbB2 and（1-100） NbB2 surface can be substituted by Al to form（Al,Nb）B2 intermedia layers.In addition,a layer of NbAl3-like compound（NbAl3 ’） can cover the surface of NbB2 with the orientation relation of（1-100）[1 1-2 0] NbB2//（110）[110]NbAl3 ’.Both of the（Al,Nb）B2 and NbAl3’intermedia layers contribute to enhancing the nucleation potency of NbB2 particles.These discoveries provide fundamental insight to the grain refining mechanism of the Nb-B based refiners for Al-Si casting alloys and are expected to guide the future development of stronger refiners for Al-Si casting alloys.
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