Thermodynamics of Nitrogen Solubility and Nitride Formation in Fe–Cr–Ti–Al–Si–N Alloy Melts

Thermodynamic behavior of nitrogen in Fe–Cr–Ti–Al–Si–N alloy melts was investigated by measuring the nitrogen solubility and solubility product of TiN and AlN by the metal/gas and metal/nitride/gas equilibration techniques at 1823–1873 K, respectively. The nitrogen solubility data measured in Fe–Cr–Ti, Fe–Cr–Si, Fe–Ti–Al and Fe–Cr–Al alloy melts was thermodynamically analyzed to determine the second-order cross-product parameters of Cr–Ti, Cr–Si, Al–Ti and Cr–Al on nitrogen in liquid iron using Wagner’s formalism. By considering the cross-product effect on nitrogen determined in the present study, the effects of the alloying elements on the solubility product of TiN and AlN in the multicomponent Fe–Cr–Ti, Fe–Ti–Al and Fe–Cr–Al alloy melts were successfully reproduced over the wide temperature range.