A material is anisotropic when it exhibits different values of a property in different directions.
These are elongated grains that form as a result of competitive growth between chill crystals during the solidification of a casting.
A0 = original cross-sectional
A ductile material is one which can undergo a large amount of plastic deformation without fracturing.
This is defined by the formula, where l0 is the original length, l is the instantaneous length, Dl is the elongation or change in length.
This is defined in the formula, where F is the applied load, and A0 is the cross-sectional area before any load is applied.
These are randomly oriented grains that form in the centre of a casting. They are roughly rounded in shape.
A small device that is fitted to the specimen to measure the change in gauge length when the elongation is very small. Gives an accurate measure of strain for the calculation of elastic modulus.
In design, the permissible load is kept below the calculated maximum load that the structure can withstand to allow for unforseen circumstances. The ratio of calculated load to the permissible load is the factor the safety.
A progressive mode of failure which occurs from cyclic loading, usually at stresses below the yield stress.
Alloys with iron as the major constituent.
The increase in average grain size of a material. Usually an elevated temperature is required for this to occur.
Working of a metal above the recrystallisation temperature
Inoculants are materials that are added to molten metal to promote a high rate of nucleation during solidification. This results in a fine grain size in the casting.
This condition exists when all components undergo equal strain. This occurs in fibre-reinforced composites when the fibres are parallel to the applied load.
This condition exists when all components are subjected to equal stress. This occurs in fibre-reinforced composites when the fibres are perpendicular to the applied load.
The fine structure of a material which can be seen at a macroscopic level, ie, without using a microscope.
The fine structure of a material which can only be seen at a microscopic level, ie, when using a microscope.
Crack is loaded solely in tension
see Young's Modulus
A composite that has equiaxed particles as the dispersed phase.
This is the condition where under tensile stress there is zero strain
in a direction perpendicular to the stress axis and the direction of crack
propagation. This exists in thick plates - the zero-strain direction is
Leads to permanent deformation of a material after the release of the applied load. This occurs after the elastic limit, and is related to permanent atomic displacements.
Eliminates residual stresses introduced during deformation, usually by a low temperature heat treatment, without reducing strength.
Formation of new strain-free grain structure in a previously cold-worked structure by heat treatment above the recrystallisation temperature.
Stresses that are introduced during deformation that persist when there is no longer any external force or temperature gradient present.
It states that the modulus of a unidirectional fibre composite (Ec) is proportional to the volume fractions (f) of the materials in the composite. It may also be used to determine the density of a composite.
The presence of composition differences in a material caused by insufficient time for diffusion during solidification.
The minor element (ie, added element) in a solid solution alloy. For example, in a solid solution containing 70% copper and 30% zinc, zinc is the solute.
The major element (ie, host element) in a solid solution alloy. For example, in a solid solution containing 70% copper and 30% zinc, copper is the solvent.
The ratio of strength to density of a material.
(Specific Modulus) The ratio of elastic modulus to density of a material.
This is defined as one half of the difference between the maximum stress and the minimum stress during constant amplitude stress cycling.
A thumbnail crack at the surface of a failed component:
This means 'one axis'. A uniaxial tensile test is one in which the test piece is stretched in one direction only, along its axis.
The increase in strength and hardness of a material by increasing the number of dislocations by plastic deformation or cold working.
(Modulus of elasticity) The ratio of the applied stress to the strain in a material that is deformed elastically. It is also a measure of the stiffness of a material.