8/17/2019 Specification of Composition

http://slidepdf.com/reader/full/specification-of-composition 1/4

SPECIFICATION OF COMPOSITION

Weight percent (wt%) - is the weight of a particular element relative to the

total alloy weight. For an alloy that contains two hypothetical atoms denoted

by 1 and 2, the concentration of 1 in wt%, C1, is dened as,

Atom percent (at%) - calculations is the number of moles of an element in

relation to the total moles of the elements in the alloy. he number of moles

in some specied mass of a hypothetical element 1,nm1, may be computed as

follows!

Concentration in terms of atom percent of element 1 in an alloy containing

element 1 and element 2 atoms, is dened by

Composition Conversions

Conversion of weight percent to atom percent "for a two-element alloy#

Conversion of atom percent to weight percent "for a two element alloy#

$ecause we are considering only two elements, computations involving the

preceding euations are simplied when it is reali&ed that

8/17/2019 Specification of Composition

http://slidepdf.com/reader/full/specification-of-composition 2/4

'n addition, it sometimes becomes necessary to convert concentration from

weight percent to mass of one component per unit volume of material "i.e.,

from units of wt% to (g)m*# computations. Concentrations in terms of this

basis will be denoted using a double prime "i.e., and the relevant euations

are as follows!

Conversion of weight percent to mass per unit volume "for a two element

alloy#!

Furthermore, on occasion we desire to determine the density and atomic

weight of a binary alloy given the composition in terms of either weight

percent or atom percent. 'f we represent alloy density and atomic weight by

+ave and ave, respectively, then

Computation of density "for a two element metal alloy#

Computation of atomic weight "for a two-element metal alloy#

8/17/2019 Specification of Composition

http://slidepdf.com/reader/full/specification-of-composition 3/4

8/17/2019 Specification of Composition

http://slidepdf.com/reader/full/specification-of-composition 4/4

Mi*e$ $isocations - dislocations found in crystalline materials are probably

neither pure edge nor pure screw, but ehibit components of both types.

#eporter+ Arne A ,'man

,ro'p -