Mechanisms of nanoscale structure formation during electron beam treatment of silumin

Open School-Conference of NIS Countries Ultrafine Grained and Nanostructured Materials

Sarychev, V.D.^1 ; Ivanov, Y.F.^2 ; Nevskii, S.A.^1 ; Serenkov, Y.S.^1 ; Vysotskaya, E.A.^1 ; Gromov, V.E.^1

Siberian State Industrial University, Novokuznetsk

654007, Russia^1

Institute of High Current Electronics SB RAS, Tomsk

634055, Russia^2

关键词: Capillary instability;    Electron-beam treatment;    High current electron beams;    Linear expansion coefficient;    Multilayer structures;    Nanoscale structure;    Second phase particles;    Transverse dimensions;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/447/1/012061/pdf
DOI  :  10.1088/1757-899X/447/1/012061

来源: IOP

【 摘 要 】

The effect of low-energy high-current electron beams on the structure of silumin has been studied. It has been found that the electron beam treatment leads to the formation of a heterogeneous multi-layer structure in the material. A columnar crystallization structure has been observed in the surface layer. The transverse dimensions of the columns are between 400 and 600 nm, whereas the second phase interlayer dimensions are between 80 and 100 nm. The transverse dimensions of the columns at a depth of 80 to 100 μm are 1.0-1.2 μm. The cause of the columnar structure is the thermoconcentration-capillary instability, which leads to the formation of vortices and the displacement of the second phase particles to the columnar boundaries. The considerable thickness of the columnar crystallization layer is caused by the fact that silicon and other alloying elements influence the dependence of liquid aluminum surface tension on temperature by introducing nonlinearity. As a result, there is an effect of the "thermal drill", i.e. the formation of vortices. The formed vortices stir the melt throughout the depth, and the downward flow of the liquid moves to the center of the bath at the cooling stage, which is manifested in an increase in the thickness of the columnar crystallization layer. It manifests itself in an increase in the thickness of the columnar crystallization layer. At depths over 100 μm, the fracture of silicon particles is observed as a result of differences in the elastic moduli and linear expansion coefficients of the aluminum matrix and the silicon plate.