STRUCTURAL AND PHASE FORMATION IN A MEDIUM-ENTROPY, HIGHALLOYED COMPOSITION OF THE Al-Mg-Si-V-Cr-Mn-Fe-Ni-Cu

Purpose. To obtain, in the simplest possible way, an alloy with a relatively low melting temperature for HEAs and MEAs, containing non-deficit components capable of dissolving in aluminum and exhibiting mutual solubility. The concentration of most components did not exceed 2.5–5 at.%, therefore the main was to increasing the mixing entropy was the number of elements included in the alloy composition. Research methods. The melt was prepared using a laboratory resistance furnace. Pure components and concentrated master alloys were used as charge materials, added gradually in small amounts to prevent the formation of refractory intermetallics. Melting was carried out in an alumina crucible at 1000 °C, which ensured dissolution and assimilation of all components. Results. Structural and phase characteristics of the experimental alloy were compared depending on the cristalization rate. When cooled with the furnace at a rate of 0.5 °C/s, a heterogeneous structure formed, represented mainly by three phases: an intermetallic of the Al₆Me type, based on Al₆Mn with dissolved Fe, Ni, Cr, and V; an intermetallic based on the Al₆Cu₂Ni-type phase, which by stoichiometry could be expressed as (Al,Ni)₂Cu; and the Mg₂Si phase. Rapid solidification at 5·10² °C/s resulted in some refinement of the structure and increased its homogeneity, but did not significantly change the phase composition. Notably, in the Al₆Me intermetallic, the higher-temperature compound Al₂₃V₄ became predominant. The formation of an intermetallic in the Al-Ni-Cu system under these conditions could correspond to a compound formation with the formula Al₂(Ni,Cu)₃. The Mg₂Si phase was observed as part of the eutectic (Mg₂Si+Si). Scientific novelty. A new approach to producing medium-entropy multicomponent alloys by resistance furnace melting has been demonstrated. The influence of cooling rate on phase formation in the Al-Mg-Si-V-Cr-Mn-Fe-Ni-Cu alloy has been revealed. Practical value. An approach has been developed for obtaining medium-entropy alloys from non-deficit components with a reduced melting temperature, which simplifies their synthesis. The results can be used for further studies of high-entropy and medium-entropy alloys.