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Abstract

By the method of modern physical material science (optic microscopy scanning and transmission electron microscopy) the analysis of structural phase states, the morphology of the second phase inclusions and defect substructure of Al-Si alloy (silumin) of hypoeutectic composition, subjected to electron beam processing was done with the following parameters: energy density 25-35 J/cm2, beam length 150 μs, pulse number – 3, pulse repetition rate – 0.3 Hz, pressure of residual gas (argon) 0.02 Pa. The surface irradiation results in the melting of the surface layer, the dissolution of boundary inclusions, the stricture formation of high speed cellular crystallization of submicron sizes, the repeated precipitation of the second phase nanodimentional particles. With the increased distance from the irradiation surface the layer containing the second phase inclusions of quasi-equilibrium shape along with the crystallization cells was revealed. It is indicative of the processes of Al-Si alloy structure globalization on electron beam processing.

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Authors and Affiliations

S. Konovalov
V. Gromov
D. Zaguliyaev
Y. Ivanov
A. Semin
J. Rubannikova
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Abstract

Vacoflux-49 (Fe-49% Co-49% V-2%) is used in torque, sonar and gyroscopic sensors applications due to excellent magnetic properties (high saturation magnetisation, low coercivity and high Curie temperature). In this study, the shape, size and characteristics of different thermal zones and the microstructural evolution during electron beam melting and welding of Vacoflux-49 material are studied. The experimental studies on melting have been carried out with under-focussed, focussed and over focussed electron beam. In the case of the under-focussed and over-focused beam, no evaporated zone is found. In the case of focussed beam, a shallow conical-shaped evaporated zone, a choked funnel-shaped fusion zone, a conical shaped partially melted zone and the heat-affected zone are observed. The solidified melt pool in terms of shape, size and microstructure of different zones are investigated for the focussed beam. The grains in the fusion zone appear wavy having crest and trough. The fusion zone microstructure also shows the formation of solidification rings. From the electron beam welding experiments performed for joining two Vacoflux-49 plates (continuous welding), it is found that the weldment shape is similar to the spot melting and re-solidification experiments. The grain growth in different zones in the welding sample is also examined.

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Authors and Affiliations

Pawan Kumar
Anshul Yadav
Arvind Kumar

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