Nitrogen Solubility in Mn–Si–Fe Melts

Abstract

Nitrogen solubility of two typical compositions of practical MnSi-Fe melts were measured by the gas-liquid metal equilibration technique in the range of 1 673 to 1 773 K under different nitrogen partial pressures, especially high nitrogen partial pressure close to pure nitrogen gas. It was found that nitrogen solubility increased as the increase of temperature but decreased as the increase of silicon content. The nitrogen partial pressure dependence of nitrogen solubility for 68 mass%Mn-18 mass%Si-Fe and 60 mass%Mn-30 mass%Si-Fe melts follows the Sievert's law. Relative to pure Mn melt, which doesn't obey the Sievert's law, the increase of silicon or iron content in Mn-Si-Fe melts could decrease the deviation degree from the Sievert's law. Silicon nitride precipitates were formed at the surface of the 60 mass%Mn-30 mass%Si-Fe melts at 1 773 K when the nitrogen partial pressure is 0.4.