The interface of heterogeneous nucleation on single crystal substrates

4th International Conference on Advances in Solidification Processes

材料科学;物理学

Yang, L.^1 ; Xia, M.^1 ; Li, J.^1

School of Materials Science and Engineering, Shanghai Jiao Tong University, China^1

关键词: Controlled nucleation;    Heterogeneous nucleation;    High-resolution transmission electron microscopes;    High-vacuum chambers;    Lattice misfits;    MgO substrate;    Single crystal substrates;    XRD patterns;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/117/1/012002/pdf
DOI  :  10.1088/1757-899X/117/1/012002

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Under controlled nucleation process was achieved by solidifying a high purity Al droplet on a single crystal Al2O3substrate in a high vacuum chamber. The following X-Ray Diffraction (XRD) analysis and measured undercooling prove that the nucleation was triggered by the substrate. Various lattice mismatches between new crystal and substrate (C/S) were obtained through this approach. Combining XRD patterns and high resolution transmission electron microscope analysis we found that the morphology of interface was affected by lattice misfit. An epitaxial layer was found at C/S interface with larger lattice misfit, as in Al(100)//Al2O3(0001) system. Further experiments on introduced alloying element, Sb, into liquid Al shows a suppressed epitaxial layer of Al. Chemical reaction between liquid and substrate also contributes to the formation of the interface. The nucleation of Al on the MgO substrates was actually nucleated on MgAl2O4, chemical reaction product of Al and MgO, rather than MgO.