National University of Science and Technology “MISiS”, Moscow, Russia:

E. I. Kurbatkina, Engineer

N. A. Belov, Professor, Director of Engineering Center “Innovation Casting Technologies and Materials”

A. N. Alabin, Head of Department of Engineering Center “Innovation Casting Technologies and Materials”

I. A. Sidun, Holder of a Master's Degree

Influence of interaction of chemical elements and peculiarities of phase formation in Al – B – Mg – Si – Cu system were studied, using experimental and computational techniques. Thermodynamic analysis of interfacial reactions during the melting process, was carried out for this system. Calculations have shown that formation of magnesium boride is the most probable reaction. Quantitative phase analysis, using Thermo-Calc software, confirmed theoretical calculations. In particular, the calculation of the phase composition of the alloy Al – 0.6% Mg – 0.6% Si – 0.2% Cu – 2% B showed that boron containing phase was formed by aluminum and magnesium. The concentration of magnesium in aluminum solid solution during the complete solidification was 0.02 % (wt.), which suggested the impossibility of hardening after aging in this alloy. The main objects in the experimental study were Al – B – Mg – Si – Cu system alloys. Melting was carried out in an induction furnace “RELTEC”. As a result, ingots after casting had the following dimension: 40150270 mm. Chemical composition of the alloys was determined by optical emission spectrometer ARL 4460. The spectral atomic emission method with an inductively coupled plasma was used for determination of the boron content. Measurements were performed on a spectrometer iCAP 6300 Radial View. Ingots were rolled, and sheets were under the heat treatment in the electrical muffle furnaces SNOL 8.2/1100 and SNOL 58/350. Structure was studied on scanning electron microscope Tescan Vega 3 with local microanalysis (Oxford Instruments). Sheets were subjected to mechanical tests on a tensile testing machine Zwick Z250 according to the State Standard 1497–84. Reaction of magnesium with boron was at the melting temperatures of 850–1050 ^°C. Introduction of additional magnesium (up to ~ 1.5%) in the Al – B – Mg – Si – Cu alloys allowed the development of a material with high strength characteristics (tensile strength 300 MPa), due to precipitation hardening of aluminum matrix with Mg-containing particles. Thus, increasing of boron concentration up to 3.5% did not degrade the mechanical properties of the alloy. There was found that Al – Mg – Si – Cu – B alloys, containing up to 3.5% of B, show good processability during rolling, which allows to obtain ingots of sheets with deformation degree of at least 91%.

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