Unformatted text preview: sformations in steels are athermal. through any other
material? Why are steels able to (APF)
ted with the electron holes
atomic packing factor resist considerable impact loading (rapid hammerlike
The fraction of space
blows) while ceramics shatter under relatively small impact loads? Why are oxide and
ration of a Group II or III
ﬁlled by spherical atoms.
polymer glasses transparent while other materials are opaque? Why do some materials
expand more scale structure
atomic than others when heated? structure of a material on
We often take for granted the intrinsic properties of engineering materials. If we are
A mechanism by which the
the sizestructureof an atom (i.e., on the scale of about 10 8it becomes
scale of materials to enhance their properties, however,
to alter the1 0
n some systems. It occurs when
to 10 to develop a thorough understanding of why materials behave the way they do.
rosion process has a high
Although the properties of materials depend on all levels of structure, many properties
austenite The face-centered cubic (FCC) form of iron.
are determined by the atomic scale structure alone. By atomic scale structure we mean:
he whole process is slowed
(1) The FCC phasepresent, (2) the types of bonding between the atoms, and (3) the
the types of atoms in iron alloys is also referred to as
way the atoms are packed together.
In this chapter we will brieﬂy review the structure of the atom and some basic
ocess by which two parts are
bainite A two-phase microstructure consisting the
principles of thermodynamics and kinetics. We will then describe of characteristics of
is process is used to join
the ferrite types of bonds between atoms and the way in whichaustenitic of atoms are
various and cementite. Bainite forms when an small groups
s, metals, and ceramics and
spatially arranged. We will also temperature below the pearlite scale structure
steel is quenched to a explore the relationships between atomic
and engineering properties and attempt to answer the questions we have pose...
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