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

N. A. Belov, Chief Researcher of a Chair “Metal Forming”
E. A. Naumova, Assistant Professor of a Chair “Metal Forming”, e-mail: jan73@mail.ru
V. V. Doroshenko, Engineer of a Chair “Metal Forming”
T. A. Bazlova, Assistant Professor of a Chair “Casting Technologies and Art Material Processing”

A calculation method was used to research the composition of Al – Ca – Mn – Fe system aluminium alloys, which enabled a substantiation of optimal concentrations of calcium, manganese and iron. In order to determine the concentration limits for appearance of primary crystals of intermetallic phases, the projections of liquidus of this quaternary system were calculated. It was shown that with a 6% (wt.) Ca, the total concentration of Fe and Mn is less than 1%, where primary crystals are formed, containing Fe and Mn phases. By reducing the level of calcium, the area of the primary crystallization of an aluminium solid solution expands significantly. Based on the results of the calculation, the Al – 2% Ca – 1% Mn – 0.4% Fe composition was selected as the basic one. It was shown that by crystallizing alloys with such composition, the L  (Al) + Al₆(Fe, Mn) eutectic reaction should occur after forming of a small amount of primary crystals (Al), whilst the L (Al) + Al₆(Fe, Mn) quaternary phase crystallization at 613 ^оC, which is monovariant, but has a small temperature interval (less than 1%), is prohibited. Two Al – Ca – Mn – Fe (Al2Ca1Mn0.4Fe и Al4Ca1Mn0.4Fe) system alloys were researched. They were prepared in a resistance furnace in a high-purity aluminium based (99.99%) graphite-chamotte pot. Calcium, manganese and iron were introduced to the aluminium alloy in the form of double aluminium based ligatures (Al – 15% Ca, Al – 10% Mn, Al – 10% Fe). It was demonstrated that as regards the selected concentrations, practically all of the manganese is contained in the aluminium matrix, whilst calcium and iron are in the multiphase, dispersedly structured eutectic. Primary crystals of the Al6(Fe, Mn) alloy were found in the Al4Ca1Mn0.4Fe alloy, which confirms the results of the calculation. On the example of the Al2Ca1Mn0.4Fe alloy it was demonstrated that the alloys that are based on an aluminium-calcium based eutectic can be highly processable during mould casting and pressurized processing, respectively.

This work was carried out within the Subsidiary Agreement No. 14.578.21.0220 (unique identifier: ПНИЭР RFMEFI57816X0220) of the Ministry of Education and Science of Russian Federation in realisation of the Federal Target Program “Investigations and developments on the priority ways of development of scientific-technological complex of Russia for the period of 2014–2020”.

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