International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The thermodynamic properties of the melts of the Fe–Mn(Ti)–Si, Fe–Mn–Ti, and Mn–Si–Ti ternary systems at 1873 K were studied using the “geometric” and “analytical” Redlich-Kister-Mujian models from reliable analogous data for binary boundary subsystems. Special attention is paid to the precise thermodynamic properties of melts of the Fe-Mn, Fe-Si, and Mn-Si systems, with analysis of new data for the Si-Ti, Fe-Ti, and Mn-Ti systems. Very negative deviations from ideal solutions were established for the activities of the components in melts of the Fe-Mn-Si system. In the melts of the Fe–Mn(Ti)–Si, Fe–Mn–Ti, and Mn–Si–Ti ternary systems, the minimum mixing enthalpies are observed in binary melts, and in the Fe–Mn–Si system, the minimum occurs in the Fe0.4Mn0.2Si ternary melt 0.4, because the double Fe(Mn)– Si subsystems make the largest contribution to the interaction energy between different atoms. This study demonstrates the ability to predict the thermodynamic behavior of ternary systems, allowing for optimization of alloy compositions and improvement of industrial processes. Calculations based on the Redlich-Kister-Mujianu model with a triple contribution of -200 kJ/mol for melts of the Fe–Mn–Si system agree with experimental data, which confirms sufficiently high accuracy predicted parameters.

Crystal structure, morphology, peculiarities of martensitic transformation and shape memory effect were investigated in Fe-Mn-(Si,Ge) and Fe-Mn-(Si,Sn) as-cast alloys. It was found that regularly substitution of atoms Si with the Ge or Sn in Fe-Mn-Si alloys dramatically change the martensitic transformation behavior that displayed in calorimetry, resistometry and dilatometry curves during the cooling and heating the alloys. Crystal structure changed as well. As a result of alloying by Ge and Sn the substructure of samples became more inhomogeneous, well developed dendritic structure appeared, finally (Mn0.5Fe0.5)3Sn2 phase and hexagonal phase with the structure 63/ have precipitated in Fe-Mn-(Si,Sn) and Fe-Mn-(Si,Ge) respectively. The effect of alloying with Si or Ge on γ→ε temperatures of martensitic transformation, volume effect of transformation, Neel point caused by the influences of alloying components as well as the ferromagnetic phases appearing during as-cast process.