The number of the section in which a symbol is introduced or explained is given
in parentheses.

A = area
Å = angstrom unit
Ai = atomic weight of element
APF = atomic packing factor
a = lattice parameter: unit cell
x=axial length
a = crack length of a surface crack
at% = atom percent
B = magnetic flux density
Br = magnetic remanence
BCC = body-centered cubic crystal structure
b = lattice parameter: unit cell
y-axial length
b = Burgers vector
C = capacitance
Ci = concentration (composition) of component i in wt%
C= concentration (composition) of component i in at%
Cv, Cp = heat capacity at constant volume, pressure
CPR = corrosion penetration rate
CVN= Charpy V-notch
%CW = percent cold work
c = lattice parameter: unit cell
z-axial length
c = velocity of electromagnetic radiation in a vacuum
D = diffusion coefficient
D = dielectric displacement
DP = degree of polymerization
d = diameter
d = average grain diameter
dhkl = interplanar spacing for planes of Miller indices h, k, and l
E = energy
E = modulus of elasticity or Young’s modulus
Ef = Fermi energy
Eg =band gap energy
Er(t)= relaxation modulus
%EL = ductility, in percent elongation
e = electric charge per electron
e= electron
erf =Gaussian error function
exp= e, the base for natural logarithms
F = force, interatomic or mechanical,Faraday constant
FCC = face-centered cubic crystal structure
G = shear modulus
H = magnetic field strength
Hc =magnetic coercivity
G =shear modulus
H = magnetic field strength
Hc = magnetic coercivity
HB = Brinell hardness (
HCP = hexagonal close-packed crystal structure
HK = Knoop hardness
HRF = Rockwell hardness: B and F scales
HR15N, HR45W = superficial Rockwell hardness: 15N and 45W
HV = Vickers hardness
h =’s constant
(hkl) = Miller indices for a crystallographic plane
I = electric current
I = intensity of electromagnetic radiation
i = current density
iC = corrosion current density
J = diffusion flux
J = electric current density
Kc = fracture toughness
KIc = plane strain fracture toughness for mode I crack surface displacement
k = Boltzmann’s constant
k = thermal conductivity
l =length
lc = critical fiber length
ln =natural logarithm
log = logarithm taken to base 10
M = magnetization
N = number of fatigue cycles
NA = Avogadro’s number
Nf = fatigue life
n = principal quantum number
n = number of atoms per unit cell
n = strain-hardening exponent
n = number of electrons in an electrochemical reaction
n =number of conducting electrons per cubic meter
n =index of refraction
n= ceramics, the number of formula units per unit cell
ni = intrinsic carrier (electron and hole) concentration
P = dielectric polarization
P–B ratio =Pilling–Bedworth ratio
p = number of holes per cubic meter
Q = activation energy
Q = magnitude of charge stored
R = atomic radius
R =gas constant
%RA = ductility, in percent reduction in area
r = interatomic distance
r = reaction rate
rA, rC = anion and cation ionic radii
S = fatigue stress amplitude
SEM = scanning electron microscopy or microscope
T = temperature
Tc = Curie temperature
TC = superconducting critical temperature
Tg = glass transition temperature
Tm = melting temperature
TEM = transmission electron microscopy or microscope
TS = tensile strength
t = time
tr = rupture lifetime
Ur = modulus of resilience
[uvw] = indices for a crystallographic direction
V = electrical potential difference
VC= unit cell volume
VC = corrosion potential
VH = Hall voltage
Vi = volume fraction of phase i
v = velocity
vol% = volume percent
Wi = mass fraction of phase i
wt% =weight percent
x = length
x = space coordinate
Y = dimensionless parameter or function in fracture toughness expression
y = space coordinate
z = space coordinate
lattice parameter: unit cell y–z interaxial angle
phase designations
l = linear coefficient of thermal expansion