According to the ion and molecule coexistence theory, the activity model of FeSiB ternary system was established, and the influence of ratio xSi/xFe, boron content and temperature, etc on the activity of the melt compound was investigated. The results show that the FeB activity is high in the liquid iron, when xSi/xFe is 05; the activity of boron increases with increasing the boron content for different contents of xFe and xSi, and the activity of boron at the ratio xFe=04 is about one order of magnitude higher than that for the xFe=08; The activities of the melt compound were also affected by temperature, but the influencing extent was little. The equal activity diagrams of silicon and boron were drawn for the first time according to the model results.

According to the ion and molecule coexistence theory, the activity model of FeSiB ternary system was established, and the influence of ratio xSi/xFe, boron content and temperature, etc on the activity of the melt compound was investigated. The results show that the FeB activity is high in the liquid iron, when xSi/xFe is 05; the activity of boron increases with increasing the boron content for different contents of xFe and xSi, and the activity of boron at the ratio xFe=04 is about one order of magnitude higher than that for the xFe=08; The activities of the melt compound were also affected by temperature, but the influencing extent was little. The equal activity diagrams of silicon and boron were drawn for the first time according to the model results.