INVESTIGATIONS ON SOLIDIFICATION DURING IN-SITU MICROWAVE CASTING OF METALLIC MATERIALS

Abstract

Tailoring microstructures in metallic materials is crucial as it directly influences their mechanical properties, durability, and performance. Fine-tuning of microstructures allows enhanced strength, ductility, corrosion resistance, etc. Components with specially oriented microstructure, in general, exhibit better thermo-mechanical and physical properties at elevated temperatures, for example, creep resistance, fatigue resistance, tensile strength, ductility, elasticity, and thermal shock resistance capability. Further, functionally graded materials (FGMs) exhibit gradual variations in composition and structure, enhancing their performance in terms of thermal resistance, mechanical strength, corrosion resistance, etc. Such tailoring of microstructure in metallic materials can be achieved through a process known as directional solidification (DS). In DS, heat is extracted in a specific direction from the molten charge to establish a temperature gradient that aligns the structure in a preferred orientation. In addition, application of an external magnetic field can cause further transitions in microstructure and fabrication of functionally graded materials. Many techniques were employed to achieve directional solidification, aligning with the specific material requirements and applications. In these techniques, various types of heating sources were used, such as induction heating, resistance heating, arc melting, and radio frequency heating. High initial and operational costs, inefficient heat transfer between source and target material, and higher energy requirements are some of the drawbacks of the existing methods that call for innovative approaches.