A vapour-pressure study of the [gamma] phase in copper-manganese alloys.

The thermodynamic properties of the copper-manganese system were determined by the measurement of the vapour pressure of manganese tagged with Mn⁵⁴, using the Knudsen effusion method. Manganese shows a positive deviation from Raoult's law over the entire composition range. Copper, although showing a strong positive departure from Raoult's law at low copper content, shows a slight negative departure in copper-rich compositions. The negative departure, which can be associated with an affinity of copper for manganese is greatest at compositions of about 35% manganese. The behavior of both copper and manganese is much more ideal at lower manganese compositions. The ideal behaviour of the manganese in the alloys of low manganese content and the affinity of copper for manganese at about 35% manganese appear to corroborate Myers interpretation of the electronic configurations of copper and manganese in this system.Applied Science, Faculty ofMaterials Engineering, Department ofGraduat