Chapters authored
Effect of Grain Size on Superplastic Deformation of Metallic Materials
The superplastic deformation exhibited by metals with different grain sizes and their corresponding deformation mechanism influences the industrial metal-forming processes. The coarse-grained materials, which contain grain size greater than 20 μm, exhibited superplastic deformation at high homologous temperature and low strain rate of the order of 10−4 s−1. Fine grain materials (1–20 μm) are generally considered as favorable for superplastic deformation. They possess high-strain-rate sensitivity “m” value, approximately, equal to 0.5 at the temperature of 0.5 times the melting point and at a strain rate of 10−3 to 10−4 s−1. Ultrafine grains (100 nm to less than 1 μm) exhibit superplasticity at high strain rate as well as at low temperature when compared to fine grain materials. It is attributed to the fact that both temperature and strain rates are inversely proportional to the grain size in Arrhenius-type superplastic constitute equation. The superplastic phenomenon with nano-sized grains (10 nm to less than 100 nm) is quite different from their higher-scale counterparts. It exhibits high ductility with high strength. Materials with mixed grain size distribution (bimodal or layered) are found to exhibit superior superplasticity when compared to the homogeneous grain-sized material. The deformation mechanisms governing these superplastic deformations with different scale grain size microstructures are discussed in this chapter.
Part of the book: Aluminium Alloys and Composites
Magnesium Containing High Entropy Alloys
High Entropy alloys (HEAs) or Complex Concentrated Alloys (CCAs) or Multi-Principal Element Alloys (MPEAs) is a matter of interest to material scientists for the last two decades due to the excellent mechanical properties, oxidation and corrosion resistant behaviors. One of the major drawbacks of HEAs is their high density. Mg containing HEAs show low density compared to peers, although extensive research is required in this field. This chapter aims to include all the available information on synthesis, design, microstructures and mechanical properties of Mg containing HEAs and to highlight the contemporary voids that are to be filled in near future.
Part of the book: Magnesium Alloys Structure and Properties
Simulation Study of Microwave Heating of Hematite and Coal Mixture
Temperature distribution in hematite ore mixed with 7.5% coal was predicted by solving a 1-D heat conduction equation using an implicit finite difference approach. In this work, a square slab of 20 cm x 20 cm was considered, which assumed the coal to be uniformly mixed with hematite ore. MATLAB 2018a software was used to solve the equations. Heat transfer effects in this one dimensional slab having convective and radiative boundary conditions are also considered in this study. Temperature distribution is obtained inside the hematite slab by considering microwave heating time, thermal conductivity, heat capacity, carbon percentage, sample dimensions, and many other factors, such as penetration depth, permittivity, and permeability of coal and hematite ore mixtures. The resulting temperature profile used as a guiding tool for optimizing the microwave-assisted carbothermal reduction process of hematite slab which was extended to other dimensions as well, viz., 1 cm x 1 cm, 5 cm x 5 cm, 10 cm x 10 cm, and 20 cm x 20 cm. The model predictions are in good agreement with experimental results.
Part of the book: Numerical Simulation