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Effect of the chemical composition on the structure and mechanical properties of alloys of the system Mn−Al−C in the magnetic region

Research paper by O. A. Kaibyshev, R. Z. Valiev, A. Kh. Nurislamov, V. V. Stolyarov

Indexed on: 01 Oct '88Published on: 01 Oct '88Published in: Metal Science and Heat Treatment



Abstract

An increase of the manganese content of alloys of the system Mn−Al−C from 68.9 to 73.5% increases the stability of the high-temperature ε-phase, and as a result of cooling in air from the homogenization temperature the ε-phase becomes fixed in the structure.An increase of the manganese content of alloys of the system Mn−Al−C also lowers the temperatures of the beginning and end of the ε→τ-transformation and at the same time broadens its temperature interval.Enrichment of alloys of the system Mn−Al−C with aluminum or manganese relative to the optimal composition leads to the appearance of excess nonmagnetic η- and β-phases, respectively, and these lower the level of magnetization; in addition to that, in the alloy with 73.5% Mn thermal stability is impaired as a result of disintegration of the ferromagnetic phase.A small amount of η-phase (up to 15%) lowers the deformability of the alloy, which manifests itself in higher yield stresses and lower ductility, but when the alloy contains the same amount of β-phase, it leads to a considerable lowering of the yield stress.