The electronic microcircuit industry has placed severe demands on metal suppliers to provide metals of the highest reproducible purity attainable as a result of the constant quest for the true values of physical and chemical properties of metals. This article describes the commonly used methods for ultrapurification of metals produced by electrolytic processes, including fractional crystallization, zone refining, vacuum melting, distillation, chemical vapor deposition, and solid state refining techniques. In addition, it describes the trace element analysis and resistance-ratio test methods used to characterize purity. Tables list the values for resistance ratios of zone-refined metals and their corresponding chemical compositions, and provide an example of the detection of impurities to concentrations in the parts per billion range, utilizing a combination of the glow discharge mass spectroscopy method and Leco combustion methods.

Thermal analysis is a classical method of determining phase diagrams and can be used to analyze the deviation from solidification under equilibrium conditions. This article discusses the use of thermal analysis in industrial processes and in research. It describes the theoretical basis of simplified and differential thermal analysis. Techniques for determining liquidus and solidus temperatures using cooling curves are also discussed.

Macrosegregation refers to spatial compositional variations that occur in metal alloy castings and range in scale from several millimeters to centimeters or even meters. This article presents a derivative approach for understanding the mechanism of macrosegregation induced by flow of the liquid and movement of the solid with examples.

Primary silicon in hypereutectic aluminum-silicon alloys is very hard, not only imparting improved wear resistance but also decreasing tool life during machining. This article discusses the importance of primary silicon refinement and the process of accomplishing primary silicon refinement.

Directionally solidified (DS) and single-crystal (SX) superalloys and process technology are contributing to significant advances in turbine engine efficiency and durability. These gains are expected to arise from the development of higher creep strength and improved oxidation-resistant SX alloy compositions as well as from the development of SX casting and fabrication technology to utilize advanced transpiration-cooling schemes. This article provides a detailed discussion on the chemistry and castability of first- and second-generation DS and SX superalloys. It summarizes the chemistry modifications applied to MAR-M 247 to develop CMSX-2 with respect to function and objectives. The article also lists the nominal compositions of first- and second-generation DS and SX superalloys.