THERMODYNAMIC PROPERTIES OF HCP IRON AND IRON-RUTHENIUM ALLOYS

Specific heat measurements on a series of hexagonal close packed iron-ruthenium alloys have been performed between 60°K and 300°K. Measurements of the vapor pressure of iron over f.c.c. and h.c.p. iron-ruthenium alloys have been performed at 1600°K. The results have been employed to describe the lattice stability of h.c.p. 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 h.c.p. iron exceeds that of the b.c.c. form of iron. © 1968.