THERMODYNAMIC PROPERTIES OF HCP IRON AND IRON RUTHENIUM ALLOYS.

Specific heat measurements on a series of hexagonal close packed iron-ruthenium alloys was performed between 60K and 300K. Measurements of the vapor pressure of iron over fcc and hcp iron-ruthenium alloys was performed at 1600K. The results were employed to describe the lattice stability of hcp iron and the thermodynamic properties of the iron-ruthenium system for comparison with earlier results estimated on the basis of high pressure and martensitic transformation data. In support of the theoretical conclusions deduced earlier, and in contrast to present views, the vibrational entropy of hcp iron exceeds that of the bcc form of iron. Author