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Note for Metallurgy and Materials Engineering - MME by Abhimanyu Dash

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BME 205 Materials Engineering (M) B. Tech, 4th Semester Veer Surendra Sai University of Technology, Burla, Sambalpur, Odisha Course Coordinator 1. Renu Kumari Assistant Professor Department of Metallurgical & Materials Engineering (MME) Email: renumetalbit@gmail.com, Mob. No-09564452009 2. Suneeti Purohit Assistant Professor Department of Metallurgical & Materials Engineering (MME) E-mail: suneeti.purohit@gmail.com Mob. No: (+91) 8339037187 3. Gautam Behera Assistant Professor Department of Metallurgical & Materials Engineering (MME) Email: gautamiitkgpian@gmail.com, Mob. No: +91 7855856611 1

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Module-1 Introduction of Materials Science and Engineering Materials Science – Investigating relationships that exist between the structure and properties of materials. Materials Engineering – On the basis of these structure-property correlations, designing or engineering the structure of a material to produce a pre-determined set of properties. Structure Structure of a material usually relates to the arrangement of its internal components.  Subatomic - Structure involves electrons within the individual atoms and interactions with their nuclei.  Atomic level- structure encompasses the organization of atoms or molecules relative to one another.  Microscopic – Which contains large groups of atoms that are normally agglomerated together.  Macroscopic – Viewable with the naked eye. Property A property is a material trait in terms of the kind and magnitude of response to a specific imposed stimulus. Properties are made independent of material shape and size. Example A specimen subjected to forces will experience deformation,  A polished metal surface will reflect light. Properties of solid materials may be grouped into six different categories: (1) mechanical, (2) electrical, (3) thermal, (4) magnetic, (5) optical and (6) deteriorative. The four components of the discipline of materials science and engineering and their interrelationship. 2

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Classification of Materials Solid materials have been conveniently grouped into three basic classifications: (1) metals, (2) ceramics, and (3) polymers. Metals  Materials in this group are composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (for example, carbon, nitrogen, and oxygen) in relatively small amounts.  Atoms in metals and their alloys are arranged in a very orderly manner.  In comparison to the ceramics and polymers, are relatively dense.  Mechanical Property- relatively stiff and strong , ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture.  Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms.Many properties of metals are directly attributable to these electrons.  Example, metals are extremely good conductors of electricity,and heat, and are not transparent to visible light; a polished metal surface has a lustrous appearance.  Some of the metals (viz., Fe, Co, and Ni) have desirable magnetic properties. Ceramics  Ceramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides.  Examples-aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2),silicon carbide (SiC), silicon nitride (Si3N4).  Examples of traditional ceramics — clay minerals (i.e., porcelain), cement, and glass. Properties Relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals , very hard, extremely brittle (lack ductility),.highly susceptible to fracture.  Thermal and electrical Properties- Insulative to the passage of heat and electricity low electrical conductivities and are more resistant to high temperatures  Optical characteristics-Ceramics may be transparent, translucent, or opaque. 3

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Polymers  Carbon-based compounds.  Chain of H-C molecules. Each repeat unit of H-C is a monomer e.g. ethylene (C2H4), Polyethylene – (–CH2 –CH2)n.  Polymers include the familiar plastic and rubber materials.  Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (viz. O, N, and Si).  They have very large molecular structures, often chain-like in nature that have a backbone of carbon atoms. Some of the common and familiar polymers are polyethylene (PE), nylon, poly (vinyl chloride)(PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber. Properties  Low densities, not as stiff nor as strong as ceramics and metals.  Extremely ductile and pliable (i.e., plastic).  Relatively inert chemically and unreactive in a large number of environments. Limitations  Tendency to soften and/or decompose at modest temperatures, which, in some instances,limits their use.  Low electrical conductivities and are nonmagnetic. Composites  A composite is composed of two (or more) individual materials, which come from the categories discussed above—viz., metals, ceramics, and polymers.  Objective-to achieve a combination of properties that is not displayed by any single material Examples  Cemented carbides (WC with Co binder)  Plastic molding compounds containing fillers  Rubber mixed with carbon black 4

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