Application of an adiabatic calomimeter to the determination of the heats of fusion and heats of formation of several metallic compounds
High temperature thermodynamic properties of metal alloys and refractory materials are important in both research and engineering. Reliable and precise measurements are difficult to make and require rather elaborate equipment. In recent years a commercial adiabatic calorimeter has been made available by the Rigaku Denki Company, Ltd., of Tokyo, Japan. The general operating principles of this apparatus are summarized; its application to the measurement of heats of fusion and transformation of materials, and heats of formation of intermetallic phases is described. The results of the heat of formation experiments are: MgZn2 @863° K, -4. 30 kcal/ g-atom; CaMg2 @532° K, -3. 12 kcal/ g-atom; and CeZn @623° K, -10. 6 kcal/ g-atom. The results of the heat of fusion of the materials are: MgZn2, 9. 687 kcal/mole; CaMg2, 11. 744 kcal/mole; CeZn, 7. 826 kcal/mole. The average values for the heats of fusion are accurate to ±2 pct.