Modification of the sample's surface of hypereutectic silumin by pulsed electron beam

M E Rygina,E A Petricova,A P Lasconev,V V Uglov,N N Cherenda,A D Teresov,M V Astashinskay,Yu F Ivanov

doi:10.1088/1757-899x/124/1/012138

Abstract

The article presents the results of the analysis of the elemental and phase composition, defect substructures. It demonstrates strength and tribological characteristics of the aluminium-silicon alloy of the hypereutectic composition in the cast state and after irradiation with a high-intensity pulsed electron beam of a submillisecond exposure duration (a Solo installation, Institute of High Current Electrons of the Siberian Branch of the Russian Academy of Sciences). The research has been conducted using optical and scanning electron microscopy, and the X-ray phase analysis. Mechanical properties have been characterized by microhardness, tribological properties - by wear resistance and the friction coefficient value. Irradiation of silumin with the high-intensity pulsed electron beam has led to the modification of the surface layer up to 1000 microns thick. The surface layer with the thickness of up to 100 microns is characterized by melting of all phases present in the alloy; subsequent highspeed crystallization leads to the formation of a submicro- and nanocrystalline structure in this layer. The hardness of the modified layer decreases with the increasing distance from the surface exposure. The hardness of the surface layer is more than twice the hardness of cast silumin. Durability of silumin treated with a high intensity electron beam is ≈ 1, 2 times as much as the wear resistance of the cast material.

Highlights

The application of hypereutectic silumin is limited due to its structure instability conditioned by, in particular, its uneven distribution in the castings of relatively large crystals of primary silicon and intermetallic inclusions
Investigations of the phase composition of the original alloy have revealed the presence of the two main phases – a solid solution based on alumina and a solid solution based on silicon – in the material
Mechanical properties were characterized by microhardness, tribological properties – by resistance to wear and friction coefficient

Summary

Introduction

The application of hypereutectic silumin is limited due to its structure instability conditioned by, in particular, its uneven distribution in the castings of relatively large crystals of primary silicon and intermetallic inclusions. Segregation of primary silicon crystals in hypereutectic silumin leads to worsening of castings cutting, anisotropy of the alloy properties in the cross section of castings, a relatively low level of mechanical properties and, first of all, ductility, wear resistance reduction of products. In order to suppress primary crystallization of a silicon phase it is proposed:. Published under licence by IOP Publishing Ltd

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