On the strain dependence of the activation volume in irradiated vanadium
- PDF / 189,118 Bytes
- 2 Pages / 594 x 846 pts Page_size
- 78 Downloads / 146 Views
hibiting strain hardening (comparable stress-strain curves are reported in early publications on fcc metals3). The activation volume for irradiated vanadium a p p r o a c h e s the l e v e l f o r u n i r r a d i a t e d v a n a d i u m a t t h e s a m e s t r a i n Eli m a n d s e e m s to b e c o n s t a n t b e y o n d this point. A similar phenomenon has been observed previously i n i r o n %S a n d w a s e x p l a i n e d b y a d r a g g i n g m e c h a n i s m , w h e r e c a r b o n a n d / o r n i t r o g e n a r e i n v o l v e d . In a n o t h e r p u b l i c a t i o n 6 i t w a s p o i n t e d out t h a t t h e d e c r e a s e of v
1. E. S. Tankins, N. A. Gokcen, and G. R. Belton: Trans. TMS-AIME, 1964, vol. 230, pp. 820-26. 2. N. A. Gokcen and E. S. Tankins: J. Metals, 1962, vol. 14, pp. 584-87. 3. Selected Values of Chemical Thermodynamic Properties, National Bureau of Standards, Series III, 1956. 4. C. Wagner: Thermodynamics of Alloys, Addison-WesleyPress, Cambridge, Mass., 1952. 5. T. P. Floridis and J. Chipman: Trans. TMS-AIME, 1958, vol. 212, pp. 549-53. 6. E. S. Tankins: Trans. TMS-AIME, 1969, vol. 245, pp. 1141-43. 7. M. Hansen and K. Anderko: Constitution of Binary Alloys, McGraw-Hill,Book Co., New York, 1958.
>
:'~///////Y/'~/~" ANNEALED o+ etc. IRRIADATED L6x I019 n/cm 2
E
hi
> 15 =l
Z
Q > i--
On the Strain Dependence of the Activation Volume in Irradiated Vanadium 16 22 0
V A N A D I U M of l o w i n t e r s t i t i a l c o n t e n t (~20 p p m O, 10 p p m N, 10 p p m C) e x h i b i t s no v a r i a t i o n of the a c t i v a t i o n v o l u m e v w i t h s t r a i n , w h e n t e s t e d a t low t e m peratures where no impurity atoms should be effective. The rate controlling mechanisms have been s h o w n to b e the s a m e t h r o u g h o u t t h e L ~ i d e r s a n d s t r a i n - h a r d e n i n g r e g i o n s . ~'2 H o w e v e r , a f t e r n e u t r o n i r r a d i a t i o n (1.6 • 1019n p e r s q c m , E > 1 m e v ) one o b s e r v e s a p o s i t i v e s t r a i n d e p e n d e n c e of t h e a c t i v a t i o n volume. Fig. 1 shows the results from compressive t e s t s of v a n a d i u m s i n g l e c r y s t a l s a t t e m p e r a t u r e s b e l o w r o o m t e m p e r a t u r e a n d d o w n to - 1 7 0 ~ Fig. 2 gives stress strain curves for unirradiated annealed and irradiated vanadium at room temperature and this is characteristic for all investigated temperatures. The curve for irradiated vanadium approaches t h a t f o r u n i r r a d i a t e d a f t e r a c e r t a i n s t r a i n Eli m a n d t h e n b o t h c o n t i n u e to d e f o r m in a s i m i l a r m a n n e r , e x -
540-VOLUMEl, FEBRUARY 1970
3O
STRAIN ISp, (%)
Fig. 1--Strain dependence of the activation volume for a n nealed and i r r a d i a t e d vanadium at v a r i o u s t e m p e r a t u r e s (the r e s u l t at 103~ was obtained f r o m a different b a t c h of c r y s tals).
.
m
,,
ill n~
,oJ
.~.
b--
.
r
I
i
J
I
/
i
,"r"
ANNEALED~
(D
L
"'
F
j
~~ 6Jds/sEe
ORIENTATION
Data Loading...