Alloying of Metals Approximately 80% of the one-hundred-plus elements in the periodic table can be classed as metals. A number of these possess combinations of availability and properties that lead to their use as engineering metals where mechanical strength is needed. The most widely used engineering metal is iron, which is the main constituent of […]
Deformation of Solids There are three basic types of deformation: elastic, plastic, and creep deformation. Elastic deformation is discussed next, and this leads to some rough theoretical estimates of strength for solids. Elastic Deformation Elastic deformation is associated with stretching, but not breaking, the chemical bonds between the atoms in a solid. If an external
Metals and ceramics are composed of aggregations of small grains, each of which is an individual crystal. In contrast, glasses have an amorphous or non-crystalline structure. Polymers are composed of chainlike molecules, which are sometimes arranged in regular arrays in a crystalline manner. Basic Crystal Structure of Materials The arrangement of atoms (or ions) in
Types of Material Failure A deformation failure is a change in the physical dimensions or shape of a component that is sufficient for its function to be lost or impaired. Cracking to the extent that a component is separated into two or more pieces is termed fracture. Corrosion is the loss of material due to
Diffusion in Solids A flow process that governs the movement of atoms and molecules in solids is called diffusion. The atoms and molecules change their position under influence of thermal energy, stress gradient, electric and magnetic field gradients, and concentration gradient. The process of diffusion can be easily visualized in a liquid but is more
Corrosion in Metals The destruction of metals by chemical or electro-chemical reactions with the environment is called as corrosion. Freedom of valence electrons and their conduction is responsible for corrosion in metals. Gold and platinum, the noble metals, do not corrode as they are most inactive. Products of corrosion are either porous or non-porous. These
Brittle & Ductile Fracture in Metals Separation of a solid into two or more parts under applied load or stress is called fracture. Depending on the type of load, fracture may be termed as tensile fracture, compressive fracture, shear fracture, fatigue fracture, creep fracture and cleavage fracture etc. However, these fractures are mainly characterized by
Composite material is a material system composed of two or more dissimilar constituents, differing in forms, insoluble in each other, physically distinct and chemically inhomogeneous. The resulting product possesses properties much different from the properties of constituent materials. Classification of Composite Materials Composite materials, also referred as composites, are broadly classified as Laminated composite Lamina
Ceramics are nonmetallic, inorganic, amorphous solids and are mostly metallic oxides. They have poor tensile strength, and are brittle. They can be either crystalline or noncrystalline. Many ceramics are workable in extremely low (cryogenic) temperature range, while many others are able to sustain high temperatures. Silica, silicates, NaCI, rock salt, MgO, CaF2, glasses, CsCl etc.
Chemical Heat Treatment Processes In this article I will discuss chemical heat treatment processes. (All other heat treatment processes are discussed in the previous post. This article is next part of that. So for batter understanding, also read that article.) These are: 1. Case Hardening Process (or carburising) 2. Cyniding 3. Nitriding 4. Carbo-nitriding 5.