Mechanical Properties and Tensile Testing

The ability of a material to resist deformation under applied load. Higher stiffness means less deformation for a given load.

The maximum stress a material can withstand before it breaks or permanently deforms.

The ability of a material to absorb energy before fracture. A tough material can withstand impact and bending.

The resistance of a material to indentation. A hard material is difficult to scratch.

A tensile test measures the material's response to a pulling force, which is the tensile stress.

The ratio of force (F) applied to the original cross-sectional area (A0) of the material. Units: N/m2 (Pascals).

The ratio of the change in length (ΔL) to the original length (L0). No units.

A graphical plot of stress versus strain, showing the material's behavior under tensile loading.

A type of stress that causes a material to deform by sliding or shearing along parallel planes.

The deformation resulting from shear stress, measured as the ratio of the displacement of parallel planes to their initial separation.

Stress acting equally in all directions on a solid object.

The change in volume of a material subjected to pressure, expressed as a fraction of the original volume.

The relationship between stress and strain in the elastic region of a material's response to applied force.

The point on the stress-strain curve where the material transitions from elastic to plastic deformation.

A material property representing its resistance to deformation under tensile stress.

The rate at which strain changes with respect to time.

The region on the stress-strain curve where a material undergoes permanent deformation.

The material's ability to resist deformation under shear stress. It's the ratio of shear stress to shear strain.

The material's resistance to volume change under pressure. It's the ratio of pressure change to volumetric strain.

The ratio of lateral strain to axial strain in a material under tensile stress. It's a measure of how much a material will shrink in width when it's stretched in length.

A phase of iron with a face-centered cubic (FCC) crystal structure, stable at high temperatures. Carbon can dissolve in it up to 2.1% by weight.

A phase of iron with a body-centered cubic (BCC) crystal structure, stable at room temperature. Carbon can dissolve in it only up to 0.2% by weight.

A microstructural constituent of steel, consisting of alternating layers of ferrite and cementite. It has a striped appearance.

A compound of iron and carbon (Fe3C), often found in steel microstructure. It's harder and more brittle than ferrite.

The carbon content in steel significantly affects its microstructure and properties. Low carbon content results in a softer, ductile material, while higher carbon content leads to a harder, stronger material.

A graphical representation showing phases that exist in a material at equilibrium under different temperatures, pressures, and compositions.

A specific point on a phase diagram where one phase transforms into two or more phases upon cooling. It has one phase above and two phases below.

A mixture of both liquid and solid phases of a material during solidification.

Non-uniform distribution of elements within a single grain, causing differences in chemical composition.

The rate at which a material cools down from a higher temperature to a lower temperature.

A slow cooling process where the material is kept inside a furnace for a long time.

A type of cooling where steel is allowed to cool down naturally in the air.

A very rapid cooling process used to harden steel, often using oil or water.

A metastable microstructure that is very strong and forms when steel is rapidly cooled (quenched).

A heat treatment process applied to martensite to improve toughness and ductility while sacrificing some strength and hardness.

A type of steel with relatively low carbon content, typically used for general construction applications.

A type of steel with medium carbon content, offering good strength and ductility.

A type of steel with high carbon content, known for its extreme hardness but limited ductility.

A type of steel with small amounts of added alloying elements to improve specific properties like strength, corrosion resistance, etc.

Like charges repel each other, while opposite charges attract.

The SI unit for charge, representing a fixed amount of electrical charge.

The smallest unit of charge that can exist, a fundamental quantity. It's the charge carried by a single electron or proton.

The ability of a material to store electrical energy by accumulating charges on conductive plates separated by an insulator.

The flow of electric charge through a conductor, typically measured in amperes.

A mathematical relationship describing the force between two magnetic poles, similar to Coulomb's Law for electric charges.

Materials that retain their magnetic properties even after an external magnetic field is removed. Their magnetic fields are generated by the alignment of their internal domains.

The ability of a ferromagnetic material to maintain its magnetic field after the external field is removed. It's the strength of a permanent magnet to retain its magnetization.

A measure of how much electrical energy is lost as heat in a dielectric material. It's calculated as the ratio of the imaginary part (ε'') to the real part (ε') of the complex permittivity (ε).

The actual energy storage capability of a material due to polarization.

Represents the energy dispersion or loss within the material in the form of heat.

A measure of a material's ability to support the formation of a magnetic field within it.

The ability of a material to store energy within itself.

The ratio of the imaginary part (µ'') to the real part (µ') of the complex permeability (µ).

The relative permittivity (εr) and permeability (µr) are both unitless and used to compare the permittivity and permeability of a material to the permittivity and permeability of free space.

A measure of a material's tendency to become magnetized in an external magnetic field. It's calculated as µr-1.

The average time an electron travels before colliding with an imperfection in the crystal lattice, resulting in a change of direction or energy loss.

The movement of electrons due to an electric field, creating a current flow. Electrons drift in the opposite direction of the electric field.

The ease with which an electron can move through a material under the influence of an electric field. Higher mobility means electrons move faster.

The movement of holes, which are the absence of electrons, under the influence of an electric field. Holes drift in the same direction as the electric field.

The measure of how easily a hole can move through a material under the influence of an electric field. Higher mobility means holes move faster.

The total current in a material is the sum of the electron drift current and the hole drift current.

The formula that describes the drift current of holes, where A is cross-sectional area, p is hole density, q is charge of a hole, µp is hole mobility, and E is the electric field.

The formula that describes the drift current of electrons, where A is the cross-sectional area, n is electron density, q is charge of an electron, µn is electron mobility, and E is the electric field.

The total drift current in a semiconductor is determined by the contributions of both electrons and holes, taking into account their charge, concentration, and mobility.

The conductivity of a semiconductor is directly proportional to the sum of the products of the charge, concentration, and mobility of electrons and holes.

Temperature can influence the conductivity of a semiconductor by affecting the concentration and mobility of charge carriers.

A thermistor is a resistor whose resistance changes significantly with temperature. They can either have a negative temperature coefficient (NCT) or a positive temperature coefficient (PTC).

Diffusion current arises due to the non-uniform distribution of electrons and holes in a semiconductor. Carriers tend to move from areas of high concentration to low concentration.

The Einstein Relations connect the diffusion coefficient and mobility of charge carriers. These relations apply to both electrons and holes.

The barrier potential forms at the junction between an intrinsic semiconductor and an n-type semiconductor due to differences in charge carrier concentration.

The mobility (µ) of a charge carrier represents its ease of movement under an electric field, while diffusivity (D) describes its tendency to spread out due to concentration differences.

The depletion region is formed by diffusion of majority charge carriers across the p-n junction, resulting in layers of immobile ions on both sides.

Forward bias occurs when an external voltage is applied to reduce the junction's barrier potential, allowing current to flow easily.

The ability of a material to store electrical energy when a voltage is applied across its conductive plates separated by an insulator.

The electrical resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area.

The change in resistance of a material due to temperature variations. For most metals, resistance increases with temperature, while for devices like diodes, it decreases.

The maximum voltage an insulating material can withstand before its insulating properties break down and current starts flowing.

The capacitance between two conductors insulated from each other. It's a measure of how much charge is stored for a given voltage difference between the conductors.

A type of capacitor where the plates are parallel and the capacitance is dependent on the overlapping area and the separation distance between the plates.

The Seebeck effect describes the generation of a voltage across a junction of two different metals when there is a temperature difference between the two junctions.

The Seebeck coefficient is a measure of the voltage generated per unit temperature difference across a junction of two different metals.

The Peltier effect is the phenomenon where heat is absorbed or released at a junction of two different conductors when an electric current flows through it.

The Thomson effect describes the heat generation or absorption in a conductor with a temperature gradient when an electric current flows through it.

The Thomson coefficient is a measure of the heat generated or absorbed per unit current and temperature gradient in a conductor.

The Hall effect describes the development of a voltage across a conductor carrying a current when it is placed in a magnetic field perpendicular to the current flow.

Lorentz's Law describes the total force experienced by a charged particle moving in an electric and magnetic field. The force is the sum of the electric force and the magnetic force.

A Hall effect device utilizes the Hall effect to measure magnetic fields or current. When a current flows through a conductor in a magnetic field, a voltage develops perpendicular to both the current and the field. This voltage can be measured and then related to the magnetic field strength or the current.