HAL Id: jpa-00222144
https://hal.archives-ouvertes.fr/jpa-00222144
Submitted on 1 Jan 1982
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
TRANSFORMATION BEHAVIOR OF Ti50Ni47Fe3 ALLOY :I. INCOMMENSURATE AND
COMMENSURATE PHASES
C. Hwang, M. Meichle, M. Salamon, C. Wayman
To cite this version:
C. Hwang, M. Meichle, M. Salamon, C. Wayman. TRANSFORMATION BEHAVIOR OF
Ti50Ni47Fe3 ALLOY :I. INCOMMENSURATE AND COMMENSURATE PHASES. Journal de
Physique Colloques, 1982, 43 (C4), pp.C4-231-C4-236. �10.1051/jphyscol:1982430�. �jpa-00222144�
JOURNAL DE PHYSIQUE
CoZZoque C4, suppte'ment au n o 22, Tome 43, dicembre 2982 page C 4 - 2 3 1
TRANSFORMATION BEHAVIOR OF T i N i Fe ALLOY:
5 0 4 7 3
I, INCOMMENSURATE AND COMMENSURATE PHASES
C.M. H w a n g , M. M e i c h l e , M.B. Salamon and C.M. Wayman University of IZZinois, Urbana, IZZinois 61801, U. S . A.
( A c c e p t e d 9 A u g u s t 1982)
Abstract.- The t r a n s f o r m a t i o n b e h a v i o r o f TiNiFe a l l o y s o f nominal c o m p o s i t i o n T i Ni Fe has been s t u d i e d by t r a n s m i s s i o n e l e c t r o n microscopy and
di?!ra:iioi, and e l e c t r i c a l r e s i s t a n c e measurements, between room temperature and -19h°C. Based on t h e p r e s e n t r e s u l t s and complementary n e u t r o n and x-ray d i f f r a c t i o n data, charge d e n s i t y wave (CDW) phenomena and a s s o c i a t e d phase t r a n s i t i o n s were found t o be i n v o l v e d i n t h e " p r e m a r t e n s i t i c " b e h a v i o r o f t h e Ti50Ni47Fe3 a l l o y s . The c r y s t a l s t r u c t u r e o f t h e h i g h temperature p a r e n t phase was c o n f i r m e d t o be t h e CsCl(B2) s t r u c t u r e . Upon c o o l i n g below room temperature, 1/3(110) and 1/3(111) super1 a t t i c e r e f l e c t i o n s appeared,
c o i n c i d e n t w i t h t h e o n s e t o f an e l e c t r i c a l r e s i s t a n c e anomaly (increase). The
"1/3" s u p e r l a t t i c e r e f l e c t i o n s were observed t o i n t e n s i f y w i t h d e c r e a s i n g temperature, and c l o s e i n s p e c t i o n showed t h a t such r e f l e c t i o n s d e v i a t e s l i g h t l y f r o m t h e e x a c t 1/3 p o s i t i o n s r e l a t i v e t o t h e p a r e n t CsCl s t r u c t u r e , s u g g e s t i n g t h e f o r m a t i o n o f an incommensurate s u p e r l a t t i c e o v e r a 12OC temperature range. The appearance o f t h e "113" s u p e r l a t t i c e r e f l e c t i o n s i s i n t e r p r e t e d t o be a s s o c i a t e d w i t h t h e f o r m a t i o n o f CDW's. A second
" p r e r n a r t e n s i t i c ' e f f e c t was found t o o c c u r a p p r o x i m a t e l y 12OC below t h e onset o f t h e i n i t i a l "normal-to-incommendurate" t r a n s i t i o n . T h i s subsequent phase change i n v o l v e s a s t r u c t u r a l t r a n s i t i o n from a " d i s t o r t e d " CsCl p a r e n t t o a rhombohedral product, d u r i n g which t h e "113" s u p e r l a t t i c e r e f l e c t i o n s a r e s h i f t e d t o p r e c i s e 1/3 p o s i t i o n s . The rhombohedral d i s t o r t i o n i s e f f e c t e d by a homogeneous expansion a l o n g <Ill> d i r e c t i o n s , a l l o w i n g t h e l a t t i c e and CDW1s t o l o c k - i n and become commensurate.
I n t r o d u c t i o n . - Equiatomic T i N i
,
one o f t h e f i r s t known shape memory a l l o y s ( I ) , has been t h e s u b j e c t o f i n t e n s i v e i n v e s t i g a t i o n f o r t h e p a s t t w e n t y years. I t i s known t h a t TiNi undergoes a m a r t e n s i t e t r a n s f o r m a t i o n s l i g h t l y above roorn temperature.The rnartensi t e t r a n s f o r m a t i o n i n T i N i e x h i b i t s p r e m o n i t o r y o r " p r e m a r t e n s i t i c "
phenomena immediately above t h e m a r t e n s i t e s t a r t (M ) temperature, such as an e l e c t r i c a l r e s i s t i v i t y anomaly (2-7), s t r e a k s i n e l k t r o n d i f f r a c t i o n p a t t e r n s (2,3,6,8,9), and "1/3" s p o t s seen i n b o t h x-ray and e l e c t r o n d i f f r a c t i o n p a t t e r n s (6,lO). Other anomalies i n p h y s i c a l o r mechanical p r o p e r t i e s have a l s o been
reported, such as decreases i n sound v e l o c i t y (3,11), e l a s t i c modulus (12), i n t e r n a l f r i c t i o n peaks (12,13), s p e c i f i c heat peak (14,15), etc. The n a t u r e o f t h e s e
" p r e m a r t e n s i t i c " phenomena has l o n g been an enigma.
I t was observed t h a t s u b s t i t u t i n g 3% Fe f o r Ni i n T i N i can suppress t h e Ms temperature more s t r o n g l y t h a n t h e p r e m a r t e n s i t i c t r a n s f o r m a t i o n temperature
(T ) ( l h ) , t h u s s e p a r a t i n g t h e temperature range o f t h e p r e r n a r t e n s i t i c
t r % n s f o r m a t i o n from t h a t o f t h e m a r t e n s i t i c t r a n s f o r m a t i o n , t h e r e b y r e v e a l i n g a d i s t i n c t premartensi t i c phase. Thus, t h e Ti50Ni47Fe a1 l o y i s i d e a l f o r s t u d y i n g t h e p r e r n a r t e n s i t i c phenomena w i t h o u t " i n t e r f e r e n c e "
gram
t h e m a r t e n s i t i ct r a n s f o r m a t i o n .
We have undertaken a study o f t h e t r a n s f o r m a t i o n b e h a v i o r i n T i Ni Fe e s p e c i a l l y t h e n a t u r e o f t h e p r e m a r t e n s i t i c phenomena, by means o f e78cttTca3'
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1982430
super1 a t t i c e r e f l e c t i o n s were a1 so seen. T y p i c a l s e l e c t e d a r e a d i f f r a c t i o n (SAD) p a t t e r n s o f t h e " p r e m a r t e n s i t i c " phase showing t h e 1/3(110) s u p e r l a t t i c e r e f l e c t i o n s i n [100IR7 and [111IR2 zones a r e shown i n Fig. 2. The "1/3" s u p e r l a t t i c e
Fig. 2: T y p i c a l e l e c t r o n d i f f r a c t i o n p a t t e r n s o f t h e p r e m a r t e n s i t i c phase o f t h e TiS0Ni 47Fe3 a1 l o y showing 1 / 3 (110) s u p e r l a t t i c e r e f l e c t i o n s . ( a ) and ( b )
correspond t o and [llllg2 zones, r e s p e c t i v e l y .
F i g . 3: E l e c t r o n d i f f r a c t i o n p a t t e r n s showing t e m p e r a t u r e dependence of 113 (110) s u p e r l a t t i c e r e f l e c t i o n s i n t h e [1113 zone. The s u p e r i a t t i c e
r e f 1 e c t i 0% appeared around O°C and i n t e n s i f i e d w i t h d e c r e a s i n g
temperature. ( a ) 4OC, ( b ) O°C, and ( c ) -4OC.
r e f l e c t i o n s were observed t o i n t e n s i f y w i t h d e c r e a s i n g temperatures, as shown i n F i g . 3. The change o f i n t e n s i t y i s r e v e r s i b l e w i t h t e r r p e r a t u r e and i s obvious between O°C and -10°C b u t n o t s o o b v i o u s a t l o w e r temperatures. The p o s i t i o n s of t h e 1/3(110) s u p e r l a t t i c e r e f l e c t i o n s were examined c l o s e l y by measuring t h e spacing between them. The r e s u l t s o f such measurements showed t h a t t h e 1/3(110) r e f l e c t i o n s
C4-234 JOURNAL DE PHYSIQUE
d e v i a t e d s l i g h t l y f r o m t h e e x a c t 1/3 p o s i t i o n r e l a t i v e t o t h e p a r e n t CsCl s t r u c t u r e over a 12OC temperature range. More q u a n t i t a t i v e measurements on t h e i n t e n s i t i e s and p o s i t i o n s o f t h e s u p e r l a t t i c e r e f l e c t i o n s u s i n g n e u t r o n o r x - r a y d i f f r a c t i o n gave p a r a l l e l r e s u l t s .
A n t i p h a s e - l i k e microdomains (APD's) -15008 i n d i a m e t e r were r e v e a l e d i n dark- f i e l d images u s i n g t h e "1/3" r e f l e c t i o n s . A t y p i c a l example o f t h e APU's i s shown i n Fig. 4. These microdomains a r e s i m i l a r t o a n t i p h a s e domains i n o r d e r e d a l l o y s .
Fig. 4: T y p i c a l example showing a n t i p h a s e domains(AP0's) i n t h e p r e m a r t e n s i t i c phase o f t h e Ti50Ni4 F e j a l l o y . (a) dark f i e l d e l e c t r o n m i c r o g r a p h showing APU's, ( b ) c o r r e s p o n d i n g s e l e c t e d area d i f f r a c t i o n p a t t e r n showing t h e 1/3(110)
s u p e r l a t t i c e r e f l e c t i o n used f o r t h e dark f i e l d imaging, and ( c ) b r i g h t f i e l d image.
However, no APD's a r e seen i n t h e d a r k - f i e l d images t a k e n by u s i n g (100) t y p e s u p e r l a t t i c e r e f l e c t i o n s i n t h e p a r e n t phase as w e l l as i n t h e prernarten!?iic
temperature r e g i o n s . It was n o t e d t h a t APD's a r e teiilperature independent, i .e., t h e domain s i z e and shape do n o t change w i t h t e m p e r a t u r e i n t h e p r e m a r t e n s i t i c regime.
A t about 12°C below T
,
n e e d l e - l i k e microdomains f o r m i n t h e T i 50 47 .3 Ni Fe a l l o y . The t e m p e r a t u r e coPresponding t o t h e f o r m a t i o n o f t h e "needle domains w i l l be c a l l e d Td. A t y p i c a l example o f n e e d l e domains i s shown i n F i g . 5(a). F i g u r e 5 ( b ) i s t h e c o r r e s p o n d i n g SAD p a t t e r n taken from t h e e n c i r c l e d r e g i o n i n F i g . 5(a).( a ) Transmission e l e c t r o n m i c r o g r a p h showing p a r a l 1 e l need1 e domains.
'*:responding s e l e c t e d area d l f f r a c t i on p a t t e r n t a k e n f rorn b o t h t h e need1 e domains and t h e m a t r i x r e g i o n . T h i s d i f f r a c t i o n p a t t e r n i s a superimposed p a t t e r n which c o n s i s t s o f t h e [001] and [201] zones. The i n n e r " s p l i t " s p o t s correspond LO t h e [2O1IH zone. Both t # e [201IH a#d [001lH zones a r e d e r i v e d from a
zone.
The p r e m a r t e n s i t i c s t - u c t u r e o f b i n a r y T i N i was r e p o r t e d t o be rhombohedra1
(2,8). E l e c t r o n d i f f r a c t i o n p a t t e r n s o f t h e rhombohedral s t r u c t u r e o f t h e m a r t e n s i t i c phase i n Au-5Oat.%Cd a r e w e l l - e s t a b l i s h e d (18). A s e r i e s o f SAD p a t t e r n s o f t h e TiS0Ni 7Fe3 a l l o y i n t h e p r e m a r t e n s i t i c s t a t e between Td and Ms was taken. A comparison 04 t h e p r e s e n t r e s u l t s w i t h t h e SAD p a t t e r n s o f t h e
rhombohedral s t r u c t u r e ( l a ) , shows t h a t t h e y a r e i d e n t i c a l i n symmetry. I n
a d d i t i o n , n e u t r o n and x-ray d i f f r a c t i o n (19), as w i l l be d i s c u s s e d l a t e r , show t h a t t h e p r e m a r t e n s i t i c s t r u c t u r e o f T i N i F e between Td and M i s rhombohedral. The SAD p a t t e r n s a r e t h e r e f o r e indexed a c c o r d i n g t o t h e rhombohsdral s t r u c t u r e i n terms o f hexagonal i n d i c e s . The d i f f r a c t i o n p a t t e r n i n F i g . 5(b) i s i n t e r p r e t e d as a superimposed d i f f r a c t i o n p a t t e r n w h i c h c o n s i s t s o f two o r i e n t a t i o n s . The i n n e r
" s p l i t " s p o t s correspond t h e [201IH zone, w h i l e t h e o u t e r " s p l i t " s p o t s correspond t o t h e [OOl] zone. It was proven by d a r k - f i e l d imaging t h a t t h e "needle" domains correspond t! [201IH ( i n n e r s p o t s ) and t h e m a t r i x corresponds t o [ O O l l H ( o u t e r spots). Three v a r i a n t s o f "needle" domains i n a d d i t i o n t o t h e m a t r i x were u s u a l l y seen t o f o r m below T
.
The disappearance o f "needle" domains upon h e a t i n g shows some thermal hystersqs, i.e., "needle" domains c o m p l e t e l y d i s a p p e a r above T.
Amore d e t a i l e d a n a l y s i s o f t h e "needle" domains shows t h a t t h e y can be i d e n t ' i l f i e d a s t w i n s w i t h a {110} t w i n n i n g plane.
The p o s i t i o n s o f 1/3(110) t y p e s u p e r l a t t i c e r e f l e c t i o n s o f t h e p r e m a r t e n s i t i c phase below T were examined c l o s e l y . W i t h i n t h e acsuracy o f measurements, t h e s p a c i n g betwegn s u p e r l a t t i c e r e f l e c t i o n s a l o n g <110> a r e t h e same, i.e., t h e 1/3(110) r e f l e c t i o n s a r e a t e x a c t 1 / 3 p o s i t i o n s o f t h e <110> r e c i p r o c a l l a t t i c e v e c t o r . X-ray d i f f r a c t i o n (19) a1 so showed t h a t t h e "1/3" super1 a t t i c e r e f l e c t i o n s s h i f t t o e x a c t 113 p o s i t i o n s a t T and remain commensurate w i t h t h e Bragg
r e f l e c t i o n s o f t h e rhombohedral s e r u c t u r e i n t h e p r e m a r t e n s i t i c s t a t e . Td v a l u e s a r e -lZ°C and -4g°C f o r Ti50Ni47Fe3 and Ti50.1Ni46.7Fe3.2 r e s p e c t i v e l y .
D i s c u s s i o n and Conclusions.- Two phase t r a n s f o r m a t i o n s r a t h e r t h a n one a r e found t o be a s s o c i a t e d w i t h t h e p r e m a r t e n s i t i c b e h a v i o r i n t h e Ti50Ni4 Fe3 a l l o y . A t T
,
t h e f o r m a t i o n o f "1/3" t y p e s u p e r l a t t i c e r e f l e c t i o n s i s c o i n c l d e n z w ~ t h t h e s t a r t8f
t h ee l e c t r i c a l r e s i s t a n c e anomaly ( i n c r e a s e ) on c o o l ing. The APD's formed
s i m u l t a n e o u s l y when t h e c r y s t a l developed "1/3" s u p e r l a t t i c e r e f l e c t i o n s . A t a s t i l l l o w e r temperature, Td, n e e d l e - l i k e domains were seen t o form. Anomalies i n t h e temperature d e r i v a t i v e o f t h e e l e c t r i c a l r e s i s t i v i t y vs. t e m p e r a t u r e c u r v e and s p e c i f i c h e a t peak a p p e a r i n g around Td were a l s o observed (19). The m i c r o s t r u c t u r e change as w e l l as p h y s i c a l p r o p e r t y anomalies a t T i n d i c a t e t h a t a second p o s s i b l e
" p r e m a r t e n s i t i c " t r a n s f o r m a t i o n occurs a t a l o w e r t e m p e r a t u r e t h a n t h a t o f t h e f i r s t . The t r a n s f o r m a t i o n temperatures a r e T
-
OOC, Td-
-12OC and T-
-41°C and Td-
-4g0c f o r t h e Ti50Ni47Fe3 and t h e Ti50.1Ni46.7Fe3.2 a1 l o y s , r e s p e @ t i v e l y .The p o s i t i o n s o f t h e 1/3(110) s u p e r l a t t i c e r e f l e c t i o n s were found n o t a t e x a c t 1/3 p o s i t i o n s between two fundamental r e f l e c t i o n s . Neutron d i f f r a c t i o n experiments (20) showed q u a n t i t a t i v e l y t h a t t h e 1/3(110) r e f l e c t i o n s a r e d i s p l a c e d s l i g h t l y toward t h e n e a r e s t fundamental r e f l e c t i o n s by about 0.45% a t t h e onset. The s i g n i f i c a n c e o f t h i s f i n d i n g i s t h a t i t proves t h e f o r m a t i o n o f a 1/3(1-d ) ( 1 1 0 ) incommensurate s u p e r l a t t i c e w i t h d
-
0.0045. The appearance o f an incomaensurate s u p e r l a t t i c e i s s t r o n g evidence t h i t a f e r m i - s u r f a c e d r i v e n phenomena, such as t h e f o r m a t i o n o f a charge d e n s i t y wave (21) occurs i n t h e p r e m a r t e n s i t i c s t a t e o f t h e TiNiFe a l l o y s . The f o r m a t i o n o f t h e s u p e r l a t t i c e r e f l e c t i o n s i s due t o t h e CDW s u p e r s t r u c t u r e s f o r m i n g on t h e p a r e n t c u b i c s t r u c t u r e . However, t h e CDW f o r m a t i o n s h o u l d i m p l y atomic displacement o r a l a t t i c e d i s t o r t i o n . The f a c t t h a t t h e i n t e n s i t y o f t h e 1/3(1-d ) (110) s u p e r l a t t i c e r e f l e c t i o n s i n c r e a s e s c o n t i n u o u s l y from z e r o on c o o l i n g i m p t i e s a c o n t i n u o u s change o f o r d e r parameter w h i c h i s an i n d i c a t i o n o f a second o r d e r normal-to-incommensurate phase t r a n s i t i o n . 1/3(111) t y p e s u p e r l a t t i c e r e f l e c t i o n s were a l s o found i n t h e [ l l O ] zone e l e c t r o n d i f f r a c t i o n p a t t e r n s . X-ray d i f f r a c t i o n (19) showed q u a n t % ? a t i v e l y t h e incommensurate n a t u r e o f t h e s e 1/3(1-d ) (111) s u p e r l a t t i c e r e f l e c t i o n s w i t h d2-
0.012 a t t h e onset. The n a t u r e o f t h e f i r s t p r e m a r t e n s i t i c phaset r a n s f o r m a t i o n i s t h e r e f o r e a second o r d e r normal-to-incommensurate t r a n s i t i o n w i t h t h e f o r m a t i o n o f two p o s s i b l e CDW's. The APD's a p p e a r i n g i n t h e incommensurate s t a t e o f t h e TiNiFe a1 1 oy, a r e s u g g e s t i v e o f discommensuration-type domains (22),
C 4 - 2 3 6 JOURNAL DE PHYSIQUE
although, anomalously, t h e APD s i z e i s temperature independent.
A system i n an incommensurate s t a t e can l o w e r i t s t o t a l energy by f u r t h e r t r a n s f o r m i n g t o a commensurate s t a t e , t h e so c a l l e d "lwcked i n " s t a t e . F o r t h e T i Ni Fe a l l o y , t h e 1/3(110) t y p e s u p e r l a t t i c e r e f l e c t i o n s i n t h e e l e c t r o n
,
di?!ra?iio; p a t t e r n s were found t o become s i t u a t e d a t 1/3 p o s i t i o n s a l o n g <110> a t lower temperatures i n t h e p r e m a r t e n s i t i c region. A f t e r t h e rhombohedral d i s t o r t i o n , 1/3(111) t y p e s u p e r l a t t i c e r e f 1 e c t i o n s were found by x-ray d i f f r a c t i o n (19) t o become commensurate w i t h t h e Bragg r e f l e c t i o n s a t T
.
The 1/3(111) r e f l e c t i o n s remain commensurate w i t h t h e new Bragg peak even thgugh t h e rhombohedral d i s t o r t i o n i s continuous on f u r t h e r c o o l i n g . The h i g h temperature p a r e n t phase has a c u b i c (CsC1) s t r u c t u r e and i t i s an incommensurate phase between T and T.
So t h e second" p r e m a r t e n s i t i c " t r a n s f o r m a t i o n i n v o l v e s a " d i s t o r t e d " c u b i c P t o a rdombohedral product. The rhombohedral d i s t o r t i o n i s e f f e c t e d by a homogeneous expansion a l o n g
<Ill> d i r e c t i o n s , a l l o w i n g t h e l a t t i c e and COW'S t o l o c k - i n and become
commensurate. T h i s b e h a v i o r i s d i f f e r e n t from t h e l o c k - i n mechanism i n l a y e r e d compounds (21). The h y s t e r e s i s e f f e c t i n t h e appearance and disappearance o f
"needle" domains i n d i c a t e s t h a t t h e l o c k - i n t r a n s i t i o n i s f i r s t order. Therefore, n a t u r e o f t h e second " p r e m a r t e n s i t i c " t r a n s f o r m a t i o n i n Ti50Ni47Fe3 a l l o y i s a f i r s t o r d e r incommensurate-to-commensurate CDW t r a n s i t i o n and i s a s s o c i a t e d w i t h a
" d i s t o r t e d " c u b i c t o rhombohedral t r a n s f o r m a t i o n .
Acknowledgements.- T h i s work was supported by t h e N a t i o n a l Science Foundation t h r o u g h t h e M a t e r i a l s Research L a b o r a t o r y a t t h e U n i v e r s i t y o f I l l i n o i s , Grant NSF DMR 80-20250-10. The experimental a l l o y was k i n d l y p r o v i d e d by t h e Raychem Corporation, Menlo Park, C a l i f o r n i a .
References.-
1. Buehler, W. J.,
.
1413."-.-
G i l f r i c h , J. V., and Wiley, R. C., J. Appl. Phys.,34
(1963), 2. Dautovich, D. P., and Purdy, G. R., Canadian Met. Q u a r t e r l y ,4
(1965), 129.3. Wang, F. E., DeSavage, B. F., Buehler, W. J., and Hosler, W. R., J. Appl.
Phys.,
2
(1968), 2166.4. Wayman, C. M., C o r n e l i s , I., and Shimizu, K., S c r i p t a Met.,
5
(1972), 115.5. Honma, T., Shugo, T., and Matsuvoto, Y., B u l l . Res. I n s t . o f Min. Dress. and Met., Tohoku U., 3 3 (1972), 209.
6 . Sandrock, G. D., Perkins, A. J., and Hehemann, R. F., Met. Trans.,
2
(1971),2769.
7. sandrock, G. D., Met. Trans.,
5
(1974), 229.8. Chardra, K., and Purdy, G. R., J. Appl. Phys.,
39
(1968), 2176.9. Wang, F. E., Buehler, W. J., and P i c k a r t , S. J., J. Appl. Phys.,
36
(1976), 3232.10. Otsuka, K., Sawamura, T., and Shimizu, K., Phys. S t a t . Sol.,
5
(1971), 457.11. Bradley, D., J. Acous. Soc. Am.,
37
(1965), 700.12. H a s i g u t i , R. R., and Iwusaki, K., J. Appl. Phys.,
2
(1968), 2182.13. Wasilewski, R. J., Trans. T M S - A I M E Y E (1965), 1691.
14, Dautovich, D. P., M e l k v i , Z., Purdy, G. R., and Stager, C. V., J. Appl. Phys., 37 (1966), 2513.
15.
-
Wasilewski, R. J., B u t l e r , S. R., and Hanlson, J. E., Met. Sci., J.,1
(1967), 104.16. Matsumoto, M., and Honma, T., New Asp. o f Mart. Tran. 1 s t JIM I n t . Symp. on Mart. Kobe, Japan, 1976, p. 199.
17. Thornburg, K. A., Dunne, D. P., and Wayman, C. M., Met. Trans., 2 (1971), 2302.
18. Tadaki, T., Katano, Y., and Shimizu, K., Acta Metal.,
26
(19781,883.19. Meichle, M., Ph.D. Thesis, 1981, Physics Dept. U. o f Ill. a t Urbana-Champaign.
20. Salamon, M. B., Meichle, M., Wayman, C. M., Hwang, C. M., and Shapiro, M., Proc. AIP I n t . Conf. on Modulated S t r u c t u r e s , 5 3 (1979), 223.
21. Wilson, 3. A., DiSalvo, F. J., and Mahajan, S., Adv. Phys.,
24
(1975), 117.22. McMillan, W., Phys. Rev.,
