Introduction to Materials Engineering and Metallurgy: The field of materials engineering and metallurgy includes two sections of materials science and materials engineering and is a field that is related to different scientific fields. Materials science examines the relationship between the chemical composition and microstructure of matter with its properties so that with the knowledge gained, a materials scientist can invent new materials with superior properties or improve the properties of previous materials. In contrast, materials engineering deals with how and in what way an industrial part with a specific design and shape can have predetermined mechanical, electrical, thermal, magnetic, optical, and electrochemical properties and be produced economically.
Obviously, in materials engineering, relying on the knowledge obtained from materials science, by designing and executing a manufacturing process, the desired microstructure that brings the desired properties to the part is created in the part. In addition, the design and implementation of processes in which the various elements in the periodic table are extracted from rocks and minerals in nature is another task for materials and metallurgical engineers. In recent years, the educational system of the course of materials engineering and metallurgy in university centers around the world, including our country, has been focused on metal materials, but due to the development of this field in the past few decades, the scope of this field is wide and includes vast number of materials.
From metal materials to ceramic, polymer, semiconductor and composite materials. The curriculum for students majoring in materials engineering and metallurgy is designed to include both materials science and materials engineering. Accordingly, in addition to gaining knowledge in the field of the relationship between microstructure and chemical composition with the properties of the material, the graduates of this field also have earned the necessary knowledge of various manufacturing processes of parts including casting, forming, welding, powder metallurgy, and coating and so on. Graduates in materials engineering and metallurgy are expected to be able to solve problems as well as improve and upgrade industries related to materials and metallurgy. Accordingly, the aim of the undergraduate course in Materials Engineering and Metallurgy is to train engineers who have extensive mastery of the basics of engineering and materials science and metallurgy and with the priority of metal materials in all branches related to materials can be entrepreneurship, employment or continuing education.
Classification of materials in the field of materials engineering:
Engineering materials fall into five categories Metals and alloys, ceramics, polymers, semiconductors and composites.
Metals: In general, metals fall into two categories: ferrous and non-ferrous. Ferrous metals include: cast iron and steel, non-ferrous metals include: aluminum, magnesium, zinc, titanium, copper, nickel and in general other metals and alloys other than cast iron and steel. Procurement of metals is possible through the reduction of ores and minerals.
In general, metals have good electrical and thermal conductivity. Metals and alloys have relatively high strength, high stiffness, good flexibility or ductility, and high shock resistance. They are especially useful for construction or load-bearing applications. Although pure metals are sometimes used, a combination of metals called alloys improves some properties or creates a better combination of properties.
Ceramics generally fall into two main categories :
- A: Engineering ceramics including oxides and non-oxides
- B: Traditional ceramics including clay and non-clay
Ceramics are mineral crystalline materials. In general, due to the presence of porosity (small holes), ceramics do not conduct heat well and must be heated to very high temperatures before melting. Ceramics are strong and hard but very brittle. Usually, fine powders are prepared from ceramics and a piece of ceramic with the desired shape is obtained by pressing inside the mold.
With the use of new processes, ceramics become significantly more resistant to failure, so that they can be used in load-bearing applications such as turbine blades. Ceramics are extremely resistant to pressure. Computer chips, sensors and spark plugs, inductors and electrical insulators, paints, plastics and tires are examples of where ceramics are used. Some ceramics are used as a barrier coating to preserve metal substrates in turbine engines. Old and traditional ceramics are used to make bricks, tableware, sanitary ware, sensors (heat-resistant materials) and abrasives.
Polymer: Polymers are usually organic materials. They are produced by the polymerization process. Polymeric materials include rubbers (elastomers) and many types of adhesives. Many polymers have excellent electrical resistance. They can also provide good thermal insulation. Although the strength of polymers is low, they have a very good strength to weight ratio. Generally not suitable for use at high temperatures. Many polymers have good resistance to corrosive chemicals. Polymers can be used in many applications, from bulletproof vests, CDs, ropes, and liquid crystal plates (LCDs) to coffee cups and clothing.
Semiconductors: Semiconductors based on gallium arsenide, germanium and silicon, like those used in computers and electronics, are part of a wide range of electronic materials. Electrical conductivity of semiconductor materials is between the electrical conductivity of ceramic insulators and metal conductors. Semiconductors have empowered the age of communication. In some semiconductors, the amount of conductivity can be controlled to power electrical equipment such as transistors, diodes, etc. used in the construction of integrated circuits. In many applications, we need large single crystals of semiconductors. These are made from molten material. Most thin coatings of semiconductor materials are also produced using special processes.
Composite materials: The main purpose of the development of composites is to combine the properties of different materials. Composites are composed of two or more materials and have properties that are not found in any of them. Concrete, plywood, and fiberglass are examples of composite materials. Fiberglass is made by scattering glass fibers on a polymer background. Glass fibers harden polymers without increasing density. With composites we can produce light, strong, flexible, high temperature resistant materials or on the other hand hard and shock resistant cutting tools that are crushing. In advanced aircraft and spacecraft, composites such as carbon fiber-reinforced polymers are widely used. In the manufacture of sports equipment such as bicycles, golf clubs, tennis rackets, etc., various types of composite materials are used that are light and strong.