Stability of nanoscale secondary phases in an oxide dispersion strengthened Fe–12Cr alloy

Abstract

A c t a M a t e r i a l i a 5 9 ( 2 0 1 1 ) , p p . 3 9 2 7 -3 9 3 6 DO I : h t t p : / / d x . d o i . o r g / 1 0 . 1 0 1 6 / j . a c t am a t . 2 0 1 1 . 0 3 . 0 1 7 © 2 0 1 1 A c t a M a t e r i a l i a. E l s e v i e r L t d . I n s t i t u t i o n a l R e p o s i t o r y S t a b i l i t y o f n a n o s c a l e s e c o n d a r y p h a s e s i n a n o x i d e d i s p e r s i o n s t r e n g t h e n e d F e 1 2C r a l l o y V . d e C a s t r o a , ⇑ , E .A . M a r q u i s a , 1 , S . L o z a n o -P e r e z a , R . P a r e j a b , M . L . J e n k i n s a a D e p a r tm e n t o f M a t e r i a l s , U n i v e r s i t A b s t r a c t : T r a n sm i s s i o n e l e c t r o n m i c r o s c o p y a n d a t omp r o b e t om o g r a p h y w e r e u s e d t o c h a r a c t e r i z e o n a n e a ra t om i c s c a l e t h e m i c r o s t r u c t u r e a n d o x i d e a n d c a r b i d e p h a s e s t h a t f o rm d u r i n g t h e rm o m e c h a n i c a l t r e a tm e n t s o f a m o d e l o x i d e d i s p e r s i o n s t r e n g t h e n e d F e1 2 w t .% C r0 . 4 w t .% Y 2 O 3 a l l o y . I t w a s f o u n d t h a t s om e o f t h e Yr i c h n a n o p a r t i c l e s r e t a i n e d t h e i r i n i t i a l c r y s t a l l o g r a p h i c s t r u c t u r e b u t d e v e l o p e d a C re n r i c h e d s h e l l , w h i l e o t h e r s e v o l v e d i n t o t e r n a r y o x i d e p h a s e s d u r i n g t h e i n i t i a l p r o c e s s i n g . T h e Y a n d C rr i c h o x i d e p h a s e s f o rm e d r em a i n e d s t a b l e a f t e r a n n e a l i n g a t 1 0 2 3 K f o r 9 6 h . H ow e v e r , t h e n um b e r o f C rr i c h c a r b i d e s a p p e a r e d t o i n c r e a s e , i n d u c i n g C r d e p l e t i o n i n t h e m a t r i x .K e y w o r d s : OD S f e r r i t i c s t e e l ; N a n o p a r t i c l e s ; T r a n sm i s s i o n e l e c t r o n m i c r o s c o p y ; A t omp r o b e t om o g r a p h y . I n t r o d u c t i o nT h e s t r u c t u r a l c om p o n e n t s o f f u t u r e f u s i o n r e a c t o r s w i l l b e s u b j e c t e d t o h i g h h e a t l o a d s a n d n e u t r o n fl u x e s , im p o si n g d em a n d i n g r e q u i r em e n t s o n m a t e r i a l s u s e d i n s u c h a p p l i c a t i o n s , i n c l u d i n g l ow a c t i v a t i o n , a d e q u a t e s t r e n g t h a n d t o u g h n e s s , a n d h i g h sw e l l i n g a n d c r e e p r e s i s t a n c e [ 1 ] . Am o n g t h e m o s t p r om i s i n g c a nd i d a t e m a t e r i a l s a r e r e d u c e d a c t i v a t i o n f e r r i t i c /m a r t e n s i t i c (RA FM ) s t e e l s [ 2 ] . R e d u c e d a c t i v a t i o n i n s t e e l s i s a c h i e v e d b y r e p l a c i n g s l ow -d e c a y i n g e l em e n t s s u c h a s N b , M o a n d N i w i t h o t h e r s t h a t e x h i b i t a h i g h e r d e c a y r a t e o f i n d u c e d r a d i o a c t i v i t y , s u c h a s W a n d T a [ 3 ]. H i g h -t em p e r a t u r e t e n s i l e s t r e n g t h a n d c r e e p r e s i s t a n c e i n RA FM s t e e l s c a n b...

Effect of Ti and Cr on dispersion, structure and composition of oxide nano-particles in model ODS alloys

“…In the HRTEM studies on the Fe-Y 2 O 3 alloy, ten oxide particles were analyzed and only one, with a diameter of 12 nm, was found to be monoclinic yttria and the rest of them bcc Y 2 O 3 . Our starting powder was bcc Y 2 O 3 and bulk yttria is most stable in the bcc phase up to 2598 K at atmospheric pressure [46][47][48], whereas nano-scale Y 2 O 3 particles are stabilized in the monoclinic phase owing to the increasing importance of surface effects [19,46,49]. Chang et al [50] also studied phase transformations in nano-scale Y 2 O 3 using electron microscopy and concluded that the critical grain size for the monoclinic to cubic transformation is in the range of 8-12 nm.…”

Tensile and fracture characteristics of oxide dispersion strengthened Fe–12Cr produced by hot isostatic pressing

“…[8][9][10]. The more relevant characteristics of the alloys can be summarized as follows: both ODS and non-ODS alloys present a similar microstructure, composed of martensite laths and a high density of dislocations in the as-HIPed state.…”

High-temperature oxidation resistance of ultrafine-grained 14 %Cr ODS ferritic steel

“…The oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels as a structural constituent in future fusion reactors will have to withstand high temperatures, high heat flux as well as neutron irradiation conditions [1]. Due to its unique microstructure (ultrafine grains containing oxide nanoparticles), the ODS steel has not only excellent high-temperature strength but also thermal stability.…”