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. Disciplines Ceramic Materials | Metallurgy This report is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/ameslab_isreports/99
Essential Magnesium Alloys Binary Phase Diagrams and Their Thermochemical Data
Magnesium-based alloys are becoming a major industrial material for structural applications because of their potential weight saving characteristics. All the commercial Mg alloys like AZ, AM, AE, EZ, ZK, and so forth series are multicomponent and hence it is important to understand the phase relations of the alloying elements with Mg. In this work, eleven essential Mg-based binary systems including Mg-Al/Zn/Mn/Ca/Sr/Y/Ni/Ce/Nd/Cu/Sn have been reviewed. Each of these systems has been discussed critically on the aspects of phase diagram and thermodynamic properties. All the available experimental data has been summarized and critically assessed to provide detailed understanding of the systems. The phase diagrams are calculated based on the most up-to-date optimized parameters. The thermodynamic model parameters for all the systems except Mg-Nd have been summarized in tables. The crystallographic information of the intermetallic compounds of different binary systems is provided. Also, the heat of formation of the intermetallic compounds obtained from experimental, first principle calculations and CALPHAD optimizations are provided. In addition, reoptimization of the Mg-Y system has been done in this work since new experimental data showed wider solubility of the intermetallic compounds.
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air at VA facilities, one of the many pieces of unfinished business beyond those major issues that we discussed in our Commentary. We agree that all facilities where current and past military personnel serve and receive treatment should be 100% smoke-free and note the recent Institute of Medicine report Combating Tobacco in Military and Veteran Populations. The report, which was commissioned by the Department of Defense (DOD) in 2007, calls for the DOD to set a timeline to eliminate smoking on military installations. The report also recommends that the DOD stop selling tobacco products in military commissaries and exchanges, prohibit tobacco use anywhere on military installations, and treat tobacco use in the same way as other health-related behaviors, such as alcohol abuse and poor physical fitness. We join Matthews and the Institute of Medicine in urging the VA and the DOD to take more immediate steps to protect the health of the men and women who serve in the armed services, as well as the civilians (such as Dr Matthews) working to serve them.