Manufacturing & Material Science

Point defects are defects that occur only at or around a single lattice point. They are not extended in space in any dimension.

Line defects, or dislocations, are lines along which whole rows of atoms in a solid are arranged anomalously.

A Planar Defect is a discontinuity of the perfect crystal structure across a plane. Grain Boundaries. A Grain Boundary is a general planar defect that separates regions of different crystalline orientation (i.e. grains) within a polycrystalline solid.

Bulk defects occur on a much bigger scale than the rest of the crystal defects.Bulk defect occurs when impurity atoms cluster together to form small regions of a different phase.

The presence of crystal defects in the material can change the mechanical, physical as well as the optical properties of material. Defect can affect the strength of the material. Different types of defects produce different effects. Defects also may be intrinsic due to external doping of the material or extrinsic due irradiation of material by thee high energetic ionizing radiation. Even the electrical and optical properties also change due to the presence of defects.

When a metal solidifies from the molten state, millions of tiny crystals start to grow. The longer the metal takes to cool the larger the crystals grow. These crystals form the grains in the solid metal. Each grain is a distinct crystal with its own orientation.

Grain size is the diameter of individual grains of sediment. The term may also be applied to other granular materials. This is different from the crystalline size, which refers to the size of a single crystal inside a particle or grain.

Grain structure of a solid is an arrangement of differently oriented grains, surrounded by grain boundaries.

Deformation can be permanent or temporary. Permanent deformation is irreversible whereas temporary deformation is reversible.

Stress is the force applied to a material, divided by the material's cross-sectional area. Strain is the deformation or displacement of material that results from an applied stress. In general, Stress is the force applied to a material, divided by the material's cross-sectional area. Strain is the deformation or displacement of material that results from an applied stress.

Deformation mechanism refers to the various processes occurring at micro-scale that are responsible for changes in a material's internal structure, shape and volume. The process involves planar discontinuity and/or displacement of atoms from their original position within the crystal lattice system.

In the physical sciences, a phase is a region of space (a thermodynamic system), throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization and chemical composition.

Solid solution is a solid mixture containing a minor component uniformly distributed within the crystal lattice of the major component.

Phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. A typical phase diagram has pressure on the y-axis and temperature on the x-axis. As we cross the lines or curves on the phase diagram, a phase change occurs.

A unary phase diagram plots the phase changes of one element as a function of tempera- ture and pressure. A binary diagram plots the phase changes as a function of temperature for a system with varying composition of two components.

Binary phase diagrams usually contain an assortment of single-phase materials known as solid solutions

The eutectic is made up of the liquid as well as the two phases.

Invariant reactions are reactions that show the transformation of phases. These are used in iron carbon diagrams.

Iron-carbon phase diagram describes the iron-carbon system of alloys containing up to 6.67% of carbon, discloses the phases compositions and their transformations occurring with the alloys during their cooling or heating. Carbon content 6.67% corresponds to the fixed composition of the iron carbide Fe3C.

Invariant reactions are reactions that show the transformation of phases. These are used in iron carbon diagrams.

Hardening is a metallurgical metalworking process used to increase the hardness of a metal. The hardness of a metal is directly proportional to the uni-axial yield stress at the location of the imposed strain. A harder metal will have a higher resistance to plastic deformation than a less hard metal.

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys.

In metallurgy and materials science, annealing is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness, making it more workable.

Normalizing involves heating a material to an elevated temperature and then allowing it to cool back to room temperature by exposing it to room temperature air after it is heated. This heating and slow cooling alters the microstructure of the metal which in turn reduces its hardness and increases its ductility.

Case-hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal (called the "case") at the surface.

Ultimate tensile strength, often shortened to tensile strength, ultimate strength, or within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking.

The impact strength of a material is defined as its capability to resist a sudden applied load or force. It is normally conveyed as the amount of mechanical energy absorbed in the process of deformation under the applied impact loading

Fatigue strength is the highest stress that a material can withstand for a given number of cycles without breaking. Fatigue strength is affected by environmental factors, such as corrosion. The maximum stress that can be applied for a certain number of cycles without fracture is the fatigue strength.

In materials science, creep (sometimes called cold flow) is the tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material.

A hardness test is typically performed by pressing a specifically dimensioned and loaded object (indenter) into the surface of the material you are testing. The hardness is determined by measuring the depth of indenter penetration or by measuring the size of the impression left by an indenter.

Carbon steel or plain-carbon steel, is a metal alloy. It is a combination of two elements, iron and carbon. ... With more carbon the metal gains hardness and strength but becomes less ductile and more difficult to weld. Higher carbon content lowers steel's melting point and its temperature resistance in general.

Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties.

Cast iron is a group of iron-carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature.

In metallurgy, a non-ferrous metal is a metal, including alloys, that does not contain iron in appreciable amounts. Generally more costly than ferrous metals, non-ferrous metals are used because of desirable properties such as low weight, higher conductivity, non-magnetic property or resistance to corrosion.

So this here is the last lecture of the course. I hope you understood everything.

All the very BEST !!