Zinc solubility in solid iron

The solubility of zinc in solid iron was determined by a static equilibrium method using two different types of equipment. The first apparatus used a sealed and evacuated fused silica capsule, with the zinc and iron at opposite ends of the capsule. The second apparatus used two vertical mullite or alumina tubes. One tube was partly inside the other with the zinc located on top of the inner tube. In both techniques, the temperature of the zinc fixed the partial pressure of zinc in the system. The solubility of zinc in solid iron was determined in the temperature range from 1273 K to 1673 K. The zinc vapor pressure was varied from 0.65 to 1.5 atm. The majority of the experiments were run in the austenite region of the iron-zinc phase diagram. The remaining experiments were done in the lower and delta ferrite regions. The activities and activity coefficients of zinc were determined directly from the zinc content in the iron samples, and the zinc vapor pressure, and then compared with published zinc solubility data. The results indicate that above an iron temperature of about 1200°C and below a PZn of about 1 atm there is a linear relationship between zinc vapor pressure and zinc content. Therefore, for these conditions, zinc closely approximates Henry\u27s law. The results also indicate that there is little difference between the activity coefficient of zinc in alpha and gamma iron. The segregation coefficient of zinc between liquid iron and delta ferrite iron was estimated to be between 1.55 and 2.33, depending on the data used --Abstract, page iii