Measurement of the activity of boron in liquid copper using a four-phase equilibrium technique

Abstract

The purpose of this article is to report measurements on dilute Cu-B alloys at 1723 K using a new four-phase equilibrium technique. The method can be considered as an extension of the conventional procedure involving metal-slag-gas equilibration, where the gas phase containing carbon monoxide is pre-equilibrated with graphite to define the carbon and oxygen chemical potentials. Under the reducing atmosphere, liquid diboron trioxide (B₂O₃) is partially reduced by graphite generating a liquid Cu-B alloy and carbon monoxide at controlled pressure. After quenching to room temperature, the concentration of B in the liquid copper is measured. The equilibrium boron concentration in copper is measured as a function of the partial pressure of carbon monoxide in the gas phase.