The magnetic aftereffect in iron after shock deformation
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l i o n v e c t o r . T h e k i n e t i c s of t h e a f t e r e f f e c t c a n b e d e s c r i b e d by a s h o r t - r a n g e i n t e r s t i t i a l d i f f u s i o n w h i c h relaxes the stabilization. In t h e p r e s e n t e x p e r i m e n t s , i r o n h a s b e e n s h o c k deformed and magnetic aftereffects have been invest i g a t e d a t 300~ T h i s i n v e s t i g a t i o n w a s u n d e r t a k e n to d e t e r m i n e how s h o c k d e f o r m a t i o n a l t e r s t h e k i n e t i c s a n d m a g n i t u d e of t h e a f t e r e f f e c t . The i r o n s p e c i m e n s w e r e p l a s t i c a l l y d e f o r m e d by s h o c k l o a d i n g a t p r e s s u r e s of 90, 150, 300, a n d 500 k b a r . T h e s a m p l e s of p o l y c r y s t a l l i n e i r o n w e r e in the f o r m of e l o n g a t e d t o r o i d a l c o r e s m a d e up of o n e s t r i p o f 0.2 m m s h e e t . T h e f i e l d c o i l a n d p i c k - u p c o i l w e r e wound onto the iron c o r e . The m e a s u r e m e n t technique w a s s i m i l a r to t h a t u s e d by T o m o n o s a n d R u s n a k e t a l . 6 a n d c o n s i s t e d o f a n e l e c t r o n i c a l l y t i m e d c l o s u r e of a m e a s u r e m e n t c i r c u i t at s p e c i f i e d t i m e i n t e r v a l s a f t e r t h e a p p l i c a t i o n of a m a g n e t i c f i e l d . T h e flux c h a n g e w a s m e a s u r e d f r o m the t i m e of c i r c u i t c l o s u r e until z e r o flux c h a n g e . Flux c h a n g e s w e r e d e t e c t e d on a galv a n o m e t e r . T h e m a g n e t i c - f i e l d l e v e l w a s a t 0.25 o e . Each specimen was demagnetized before a measurement was taken. The aftereffect induction ABa was measured as a f u n c t i o n of t i m e . T h e a f t e r e f f e c t i n d u c t i o n i s t h e d i f f e r e n c e b e t w e e n the m a g n e t i c i n d u c t i o n a t a n y t i m e a f t e r field application, BT, and the equilibrium induction B e , after total relaxation. The total aftereffect induction A B eT i s t h e d i f f e r e n c e b e t w e e n B e a n d B i , t h e i n s t a n t a neous induction. The instantaneous induction is taken after complete eddy current decay.
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The Magnetic Aftereffect in Iron After Shock Deformation
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has been well known that the magnetization curve of a f e r r o m a g n e t i s not a s t a t i c p r o p e r t y , but i s t i m e d e p e n d e n t . 1 Snoek 2 initially s h o w e d that a c a r b o n a t o m in b c c - F e g i v e s r i s e to t h i s m a g n e t i c a f t e r e f f e c t . A l though there exist other magnetic aftereffects,3 as well, only the diffusion-controlled aftereffect will be cons i d e r e d in t h i s p a p e r . T h e d e l a y e d r e s p o n s e to t h e a p p l i e d m a g n e t i c f i e l d i s due to t h e h i n d r a n c e to d o m a i n w a l l motion c r e a t e d by i n t e r s t i t i a l s w h o s e e n e
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