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(a)
10
-2
723K
773K
823K
873K
10
-3
5
10
-4
·
DEb
ε
kT
10
-5
1
10
-6
2
1
1
10
-7
1
10
-8
10
-4
10
-3
σ
10
-2
/E
(b)
10
-5
RD
TD
500°C
10
-6
550°C
600°C
n
= 7
650°C
10
-7
·
ε
kT
n
= 1
DEb
10
-8
500°C
550°C
n
= 3
10
-9
600°C
650°C
10
-10
10
-4
10
-3
σ
/E
10
-2
3.16
The BMD plot exhibiting the transitions in creep mechanisms in (a)
Ti-3Al-2.5V
57
and (b) Nb-modifi ed Zircaloy
73
as a function of stress and
temperature.
note that the stress exponent in the intermediate stress region is 3.5 corre-
sponding to viscous glide of dislocations or Weertman microcreep mecha-
nism. Since glide and climb occur in sequence, when lower temperatures are
approached the climb-controlled creep becomes dominant with fi ve power
law thus depicting the fact that the slower climb process controls creep. In
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