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1. Introduction
The present work addresses the problem of multi-physics-based computational modeling and analysis of the reactive melt infiltration (RMI) process used in the fabrication of ceramic-matrix composites (CMCs). Consequently, the concepts most relevant to the present work are: the basics of CMCs; RMI-processed CMCs; prior experimental work on RMI of CMCs; and prior computational work on RMI of CMCs. In the remainder of this section, a brief description is provided for each of these concepts.
1.1. The basics of CMCs
High-temperature metallic materials such as nickel, cobalt or iron-based superalloys used in gas-turbine engines have been pushed to their thermal-stability limit since they are often made to operate at temperatures which are within 50° of their melting point. To increase power density and energy efficiency of the gas-turbine engines, new materials are needed which can operate at temperatures as high as 1,400 K. The main candidate materials currently identified for use in the next generation of gas-turbine engines are (monolithic) ceramics and CMCs. Since these materials can withstand extremely high temperatures, their use in hot sections of gas-turbine engines can yield a number of benefits such as: improvements in thrust and fuel efficiency; lower pollutant emissions; reduced cooling requirements; simplification of the engine-component design; and reduced requirements for the strength/weight of the supporting structure.
However, due to their relatively low fracture toughness, tensile strength and damage tolerance, ceramics are not being perceived as respectable candidate materials for use in critical turbine-engine structural applications (e.g. turbine blades). On the other hand, CMCs consisting of a ceramic matrix and ceramic fibers possess superior structural properties relative to their monolithic-ceramic counterparts, while retaining their high-temperature stability and integrity. This is the reason that the CMCs are being aggressively researched and developed for use in future gas-turbine engines. The potential of the CMCs in revolutionizing the performance of the gas-turbine engines is shown schematically in Figure 1 (Luthra, 2014). In this figure, the x -axis represents the approximate period of dominance in usage of the particular class of high-temperature materials (and associated high-temperature technologies), while the y -axis denotes the temperature capability of the material class in question. It is seen that the temperature capability of CMCs lies above the fitting line for the temperature capabilities of...