Co
ourse 12.141
1: Elecctron Micropprobe
An
nalysiss – Pro
oblem Set 4
NiK (EK=7.478 keV
V) is highly absorbed inn Fe (Ec(K-shelll)=7.111 keV
V) with
2
(/)Fe
=379.6
6 cm /g. As a result, a po
ositive correection is appllied to the measured k-raatios
K
of NiiK in Fe-Ni alloys. On the other haand, FeK iss fluoresced as a consequuence of NiK
absorrption. A neg
gative correcction is appliied to the meeasured k-raatios of FeK
.
NiK
Probllem 4.1: Usee the averagee results obttained in Prooblem 3.1 to plot graphs of Z, A, F, and
comb
bined ZAF versus compo
osition. Expllain the variaations in Z, A, F, and ZA
AF with
comp
position.
Probllem 4.2: In a single spott analysis, th
he measured k-ratios for FeK and NiK are 0.5535
and 0.488 respecttively. Use an iterative procedure to calculate thhe concentrattions of Fe and
Ni in the alloy. The constants neeeded for the calculationss are as folloows: Z
A (g/mole) V) Ec(K-shell) (keV
Eo (keV)
()iFeK (cm
m2/g) NiK
(cm2/g) ()i
o
( )
 (K)
(r-1)/r
P
N. Chattterjee: January 2012
2, MIT, Cambridge, MA, USA
Fe
FeK keV
26
55
5.847
7 .111
15
71.4
3 79.6
40
0 .347
0 .880
1.000
1
Ni
K keV
V
NiK
28
8
58.71
2
8.332
15
5
90
0
58.9
9
40
0
0.414
4
0.880
0
1.000
0
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12.141 Electron Microprobe Analysis
January (IAP) 2012
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