Thermal Melt Processing of Metallic Alloys

Using melt superheating as a means to control the structure and properties of metallic alloys has been studied extensively and demonstrated some promising results, though the industrial implementation is limited due to the required high energy for melt heating and holding. The physical mechanisms behind this technology can be divided into two major groups: (1) achieving homogeneous metallic melt with the resultant high undercooling upon solidification and (2) formation of heterogeneous substrates either by formation or transformation of insoluble impurities. In this chapter, we first discuss the structure of melts and its changes with temperature during high-temperature holding. Although mostly of academic interest, these studies demonstrate the complexity of temperature influence on the molten and solidifying melt. Some examples on the effects of the initial melt condition on the solidification microstructures are given as well. After that we consider some practical implications of the changes in insoluble impurities with temperature on the microstructure formed during solidification in some metallic alloys.