INFLUENCE OF VARIOUS TREATMENT TYPES ON THE STRUCTURE, DENSITY, AND ELECTRICAL CONDUCTIVITY OF AL–MG SYSTEM WROUGHT ALLOYS

A comparative study was carried out to determine the effect of AlZr4, AlZr10 and AlSc2 modifying master-alloys and magnetic-pulse treatment (MPT) on the density (in liquid and solid state), electrical conductivity (in solid state) and macrostructure of AMg5 and AMg6 alloys. Molten master alloys were poured into special devices to ensure a cooling rate of ~10², ~10³ and ~10⁶ °C/s during crystallization. Master alloys were introduced into the melts at the rate of 0.01% per modifier element. It is shown that melt modification with nucleating additives contributes to higher alloy density in liquid and solid states. The electrical conductivity of the alloys with AlZr4 and AlZr10 master alloys added is lower. The AlSc2 master alloy introduction causes an increase in the electrical conductivity of AMg5 and AMg6 alloys. This effect is observed for the first time and requires additional research. It is found that the AlSc2 master alloy obtained by crystallization in a water-cooled roller mold has the greatest influence on the physical properties of alloys in comparison with AlZr4 and AlZr10 master alloys. It also provides maximum macrograin refinement. Magnetic-pulse treatment (MPT) of melts following the axial scheme of impact contributes to higher density of alloys in liquid and solid states similar to the introduction of modifying master alloys. Electrical conductivity increases after MPT as with the AlSc2 master alloy added to melts. Alloy macrograin refinement at magnetic-pulse treatment is comparable with the addition of the AlZr4 modifying master alloy. The comparative studies allow for the conclusion that magnetic-pulse treatment can be attributed to physical modification methods. The methods of density and electrical conductivity determination can be used for express evaluation of the studied effects for their modifying effectiveness.

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