Textbook: Callister’s: Materials science and engineering 10th
edition.
Authors: William D. Callister, Jr. David G. Rethwisch
Chapter 2: Introduction to materials and the family of materials:
The structure of materials:
The structure of materials relates to the arrangement of its internal
components:
Subatomic structure: Involves the electrons within the individual
atoms their energies. The interaction with the nuclei.
Atomic structure: The arrangement of atoms to yield molecules and
crystals
Nanostructure: The collection of atoms to form nanoparticles with
nanoscale dimensions. Less than 100 nm range (metals and
ceramics) or molecular chains polymer.
Microstructure: collection of structural elements in the size range of
100nm to mm to form grains in metals or fibres in polymers
Macrostructure: collection of structural elements visible by naked
eye and from mm to meters and beyond.
What is the property of a material?
It is the response of a material to a specific imposed stimulus
Mechanical properties:
Definition: The materials response/reaction to an applied load/force
Elastic modulus: Indicates the stiffness of a material (units GPa)
Yield strength: Strength at which permanent deformation starts to occur.
Materials resistance to deformation during stretching. How to calculate? –
Tensile force at which permanent deformation starts to occur divided by
the original cross-sectional area of specimen (MPa)
Tensile strength: The highest value of engineering stress where fracture
starts. Ability of a material to resist fracture during stretching. How to
calculate? Divide the tensile force at which fracture starts by the original
cross-sectional area of specimen.
Elongation to fracture: % elongation of a given gauge length (change in
length divided by original length of specimen). Elongation refers to the
degree at which a material deforms during stretching.
, Reduction in area: % Reduction in cross-sectional are (change in area
divided by original area of specimen).
Ductility: a descriptive term to the maximum deformation to fracture…can
be represented by elongation or reduction in area.
Hardness: The ability of a material to resist penetration by the other
bodies/the measure of a materials resistance to localized plastic
deformation.
Resilience: The measure of the amount of energy a material can absorb
under elastic loading conditions.
Resistance to fracture/fracture toughness: A function of resistance to
growth.
Thermal properties:
Definition: Response of a material to changes in temperature/temperature
gradient across a material.
With increasing temperature it starts to creep down (deform slowly) it may
oxidize or degrade and there is a loss of strength.
Thermal conductivity: measures the rate at which heat flows through a
material at constant temperature.
Specific heat capacity: The amount of heat required to raise the
temperature of a material by a given amount.
Thermal diffusivity: The property government transient heat flow.
Electric properties:
Definition: Materials response to an applied electric field. E.g Electrical
conductivity and dielectric constant.
Magnetic properties:
Definition: A materials response to an applied magnetic field.
Ferromagnets: The ability of a material to trap a magnetic field
permanently.
Optical properties:
Definition: a materials response to the stimulus of electromagnetic/ light
radiation.
Transparent: All light that is reflected passes through object
Translucent: Some of light reflected passes through object
Opaque: None of the light passes through object.
edition.
Authors: William D. Callister, Jr. David G. Rethwisch
Chapter 2: Introduction to materials and the family of materials:
The structure of materials:
The structure of materials relates to the arrangement of its internal
components:
Subatomic structure: Involves the electrons within the individual
atoms their energies. The interaction with the nuclei.
Atomic structure: The arrangement of atoms to yield molecules and
crystals
Nanostructure: The collection of atoms to form nanoparticles with
nanoscale dimensions. Less than 100 nm range (metals and
ceramics) or molecular chains polymer.
Microstructure: collection of structural elements in the size range of
100nm to mm to form grains in metals or fibres in polymers
Macrostructure: collection of structural elements visible by naked
eye and from mm to meters and beyond.
What is the property of a material?
It is the response of a material to a specific imposed stimulus
Mechanical properties:
Definition: The materials response/reaction to an applied load/force
Elastic modulus: Indicates the stiffness of a material (units GPa)
Yield strength: Strength at which permanent deformation starts to occur.
Materials resistance to deformation during stretching. How to calculate? –
Tensile force at which permanent deformation starts to occur divided by
the original cross-sectional area of specimen (MPa)
Tensile strength: The highest value of engineering stress where fracture
starts. Ability of a material to resist fracture during stretching. How to
calculate? Divide the tensile force at which fracture starts by the original
cross-sectional area of specimen.
Elongation to fracture: % elongation of a given gauge length (change in
length divided by original length of specimen). Elongation refers to the
degree at which a material deforms during stretching.
, Reduction in area: % Reduction in cross-sectional are (change in area
divided by original area of specimen).
Ductility: a descriptive term to the maximum deformation to fracture…can
be represented by elongation or reduction in area.
Hardness: The ability of a material to resist penetration by the other
bodies/the measure of a materials resistance to localized plastic
deformation.
Resilience: The measure of the amount of energy a material can absorb
under elastic loading conditions.
Resistance to fracture/fracture toughness: A function of resistance to
growth.
Thermal properties:
Definition: Response of a material to changes in temperature/temperature
gradient across a material.
With increasing temperature it starts to creep down (deform slowly) it may
oxidize or degrade and there is a loss of strength.
Thermal conductivity: measures the rate at which heat flows through a
material at constant temperature.
Specific heat capacity: The amount of heat required to raise the
temperature of a material by a given amount.
Thermal diffusivity: The property government transient heat flow.
Electric properties:
Definition: Materials response to an applied electric field. E.g Electrical
conductivity and dielectric constant.
Magnetic properties:
Definition: A materials response to an applied magnetic field.
Ferromagnets: The ability of a material to trap a magnetic field
permanently.
Optical properties:
Definition: a materials response to the stimulus of electromagnetic/ light
radiation.
Transparent: All light that is reflected passes through object
Translucent: Some of light reflected passes through object
Opaque: None of the light passes through object.
