Further observations on the effect of grain boundary segregation in the hydrogen embrittlement of nickel
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V(x) = T { ~ -
~ x2n~(2n) } ln. 2~rx + n ~ I n ( 2n + 1)(2n +2)
where ~ is the RiemannZeta function, offers an alternative method of calculating the P function. The results of this calculation show good agreement with the P values tabulated here.
Further Observations on the Effect of Grain Boundary Segregation in the Hydrogen Embrittlement of Nickel R. M. LATANISION
AND
H. OPPERHAUSER,
JR.
Recent work ~ has shown a very clear association bet w e e n t h e i n t e r g r a n u l a r e m b r i t t l e m e n t of n i c k e l t e n s i l e s p e c i m e n s w h i c h had b e e n d e f o r m e d in t h e p r e s e n c e of c a t h o d i c a l l y p r o d u c e d h y d r o g e n and t h e s e g r e g a t i o n of h y d r o g e n r e c o m b i n a t i o n p o i s o n s (Sn and Sb) to t h e g r a i n b o u n d a r i e s . In e s s e n c e , we h a v e a r g u e d t h a t t h e e n t r y of h y d r o g e n into t h e n i c k e l s p e c i m e n s o c c u r s p r e f e r e n t i a l l y in t h e p r o x i m i t y of g r a i n b o u n d a r y i n t e r s e c t i o n s with t h e f r e e s u r f a c e , due to t h e p r e s e n c e t h e r e i n of Sn and Sb w h i c h a c t a s h y d r o g e n r e c o m b i n a t i o n p o i s o n s and s t i m u l a t e t h e a b s o r p t i o n of h y d r o g e n b y t h e m e t a l . T h i s d o e s not, of c o u r s e , d e f i n e an a t o m i s t i c m o d e l of e m b r i t t l e m e n t w h i c h , in o u r v i e w , r e m a i n s s o m e w h a t u n c l e a r . It s e e m s , h o w e v e r , m o s t s u i t a b l e at t h i s p o i n t to i n v o k e a m o d e l w h i c h i n v o l v e s b o t h a r e d u c t i o n in c o h e s i v e s t r e n g t h due to t h e a c c u m u l a t i o n of Sn and Sb a s w e l l a s H at the g r a i n b o u n d a r i e s and an i n c r e a s e R. M. LATANISION, formerly with Martin Marietta Laboratories, is now Associate Professor, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology. Dr. Latanision is currently on leave at the Max-Planck-Institut for Eisenforschung, Diasseldorf, F.R.G.H. OPPERHAUSER, JR., is Senior Research Associate, Martin Marietta Laboratories, 1450 South Rolling Road, Baltimore, Maryland 21227. Manuscript submitted July 12, 1974. METALLURGICAL TRANSACTIONS A
ACKNOWLEDGMENTS T h e a u t h o r s w o u l d l i k e to t h a n k P r o f e s s o r for his helpful discussions.
E. Smith,
1. K. A. Jackson and J. D. Hunt: Tran~ TMS-AIME, 1966, vol. 236, p. 1129. 2. R. M. Jordan and J. D. Hunt: Met. Tran~, 1971, vol. 2, p. 340. 3. J. N. Clark and R. Elliott: MetallurgyDepartment, Universityof Manchester, England, 1974. 4. J. N. Clark: M. Sc. Thesis, Universityof Manchester, 1972. 5. W. C. Hahn: J. AppL Phy~, 1941, vol. 12, p. 62. Note Added in Proof." By means of the Euler' integral the P function seriesmay also be represented thus p ~'(3) 1 - 2 I- l-~rx-t~Xcos2y
+ sx
The followingcomputational procedure was adopted: 1) Put x = Tan0rt/2) 2) Evaluate the resultingz integralusing the Gaussn point tech
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