Wegen, Gerardus Johannes Leonardus van der

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   University of GroningenOrder-disorder transitions in ternary alloysWegen, Gerardus Johannes Leonardus van derIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1982Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Wegen, G. J. L. V. D. (1982). Order-disorder transitions in ternary alloys. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 07-06-2022SUMMARY^ , ^ h -  ! L ^  . , - - r ^ ! r -  r , , ^ ^ F  ^ 4  ^ e r - ^ ! ^ 1  a ^ E ^ ^ L  ^  r r s l o c a t i o n s  h a v eA I t t V I I V  U l l e  V q ! ! U q D  L y l / c -  U I  U ! Y - L e I  u s I s u L J ,  u !shown to  be  par t i -cu la r ly  impor tan t .  I t  i s  the i r  behav io r  wh ichd e t e r m i n e s  t h e  m e c h a n i c a l  p r o p e r t i e s  o f  c r y s t a l l i n e  s o l i d s .  I na d A i l - i n n  d i q l n a : + i ^ 6 -  n - r '  ^ l ^ r '  . i n n ^ r l ^ ^ n t .  r n l o q  i n  . r 1 / q l - : 1 1  i z a -r  v ! r f v v 4 L r V I r D  I r r 4 J  y r a y  t r r r v v  r r r  v ! j ,t i n n -  i n  l - h c  n r p r : i n i t a t - i o n  o f  n h a s e s  i n  t h e  S o l i d  S t a t e  a n d  i np h a s e  t r a n s f o r m a t i o n s .  F o r  t h e s e  r e a s o n s  k n o w l e d g e  o f  d i s l o c a -t i o n s  i s  i n d i s p e n s i b l e  f o r  m e t a l l u r g i s t s  a n d  m a t e r i a l  s c i e n t i s t s .D u e  t o  t h e  g r e a t  v a r i e t y  o f  p o s s i b l e  d i s l o c a t i o n  p r o c e s s e sw h i c h  o c c u r  d u r i n g  p l a s t i c  f l o w ,  i t  w i l l  n e v e r  b e  p o s s i b l e  o n  an r r r o r '  r h a n r a + i ^ : 1  L ^ ^ r ^  ! ^  * - ^ r ' : t  t h e  e v o r u t i o n  o f  t h e  d i s l o -y q ! s f J  L l l s v r g L t g a r  v a - a J  L v  I , r c u r (cat ion  s t ruc tu re  under  d i f fe ren t  de format ion  cond i t i -ons  and toc a l c u l a t e  t h e  m a c r o s c o p i c  p r o p e r t i e s  o f  a  m a t e r i a l  w i t h  s u f f i -^ i a h f  a - ^ 1 r r i d \ 7  P a t h a r  f n r : n  r r n d a r q f > n d i n a  n f  m a a h : n i n : l  n r n -,  ! v !n ^ r F i ^ d  f l . r a  a n n q ^ n  n r n n a A r r r a  i e  { . n  d o € . i n a  n h a n n m o n n l n a i n : I  r a -y s !  L ! s J ,  u I l E  U v l L u t t v l r  y r v u s u u ! s  l o  L v  u s ! I f r e  y l l s r l v l t l s r t v r v Y r u q !  ! el a t i o n s h i p s  e x p e r i m e n t a l l y ,  t o  c o r r e l a t e  t h e s e  w i t h  t r a n s m i s s i o ne l e c t r o n  m i c r o s c o p i c  o b s e r v a t i o n s  o n  t h e  c r y s t a l l o g r a p h y  o f  s l i pand on  the  evo lu t ion  o f  the  d is loca t ion  s t ruc tu re  and hence todeduce the  phys ica l  na ture  o f  the  cont ro l l i -ng  d is loca t ion  mecha-n j - s m s .  I n  t h i s  t h e s i s  w e  r e p o r t  t h e  r e s u l t s  o f  j - n v e s t i g a t i o n sa l o n g  t h e s e  l l n e s  o n  C u N i Z n  a l l o y s  w h i c h  s h o r v  o r d e r i n g  a s  w e l l  a sn r  r r e + o r i  n n  F ^ r  + 1 - 1 6  a r n a r a n  : r  l  n r r  c u r N i Z n  t w o  s t r u c t u r e s  a r e  p o s -e  i  h  i  a .  T . 1  a n d  T .  l  + \ r h 6  t -  h ^ +  m i  a l - r ] -  l . r : r r a  i  m n n r l a n ] -- r  y -  ,  - * , .  -  c o n s e q u e n c e sf o r  t h e  m e c h a n i c a l  b e h a v i o r .  S e v e r a l  p h y s i c a l  p r o p e r t i e s  o f  t h ea l loy  CurNiZn have been de termined as  a  func t ion  o f  the  quenchtempera ture  and/or  the  in  s i tu  tempera ture .  The resu l ts  a re  sum-m a r i z e d  i n  t h e  f o l l o w i n g :The second order  e las t i c  cons tan ts  have been measured as  afunc t ion  o f  the  quench tempera ture .  They  decrease w i th  inc reas ingq u e n c h  t e m p e r a t u r e ,  i , e .  d e c r e a s i n g  l o n g - r a n g e  o r d e r ,  u n t i l  t h eorder -d isorder  t rans format ion  tempera ture  Tc l  i s  reached.  Aboveth is  c r i t i . ca l  tempera ture  the  e las t i c  cons tan ts  a re  a lmost  inde-pendent  o f  the  quench tempera ture ,  cor respond ing  to  an  j -n te rna ls t ruc tu re  wh ich  remains  a lmost  the  same.T h e  p r e s e n c e  o f  t w o  o r d e r e d  s t r u c t u r e s  f o r  C u . N i Z n ,  a n d  h e n c ea n  o r d e r - o r d e r  t r a n s f o r m a t i o n  a t  a  c r l t i c a l  t e m p e r a t u r e  T " r ,  i sconf i rmed by  the  resu l ts  o f  accura te  measurements  o f  the  la t t j -cep a r a m e t e r .  T h e  c r i t j - c a l  t e m p e r a t u r e s  o b t a i n e d  b y  t h i s  t e c h n i q u ea r e  T  - = 7 7 5 + t 2  K  a n d  T  ^ = 5 9 5 + 7  K .c r  c zT h a  r r i a l A  c l - r ^ ^ ^  ^ c  ^ "  n r j ' *  - S  a  f U n C t j - O n  O f  t h e  q U e n C h  t e m -u ! s D D  V !  V U 2 ! \ ! ! r I  q ;pera ture  and the  de format ion  tempera ture  has  been exp la ined 1nterms o f  the  s t ress  necessary  to  opera te  a  Frank-Read source  w i tha n  i n i t i a l l y  e d g e - o r j - e n t e d  s u p e r l a t t i c e  d i s l o c a t l o n  h a v i n g  al e n g t h  o f  I . 4 5  u m .T h e  s t r a i n  h a r d e n i n g  c a n n o t  b e  e x p l a i n e d  b y  t f r e  { 1 0 0 }  c r o s s -s l i p  m e c h a n i s m  ( a s  i s  o f t e n  d o n e  f o r  t h e s e  t y p e  o f  o r d e r i n g  a 1 -I o y s ) ,  b u t  c a n  b e  i n t e r p r e t e d  b y  t h e  f o r r n a t i o n  o f  A P B  t u b e s .Duct i l i t y  measurements  a re  in  agreement  w i th  the  we l l  knownl a t e n t  h a r d e n i n g  e f f e c t  i n  t h e s e  t y p e s  o f  o r d e r i n g  a l l o y s .  S l i ppredominate ly  occurs  a t  one or  two s l ipsys tems,  wh ich  number  i sto  sma11 to  accomodate  the  complex  boundary  cond i t ions  and hencef r a c t u r e  o c c u r s  a t  s m a l l  s t r a l n s .V ickers  mlc rohardness  measurements  revea led  tha t  the  ex ten to f  A P B  d o m a i n  s t r e n g t h e n i n g  i n  C u r N i Z n  i s  s m a l l .  T h e  m i c r o h a r d -ness  as  a  func t ion  o f  the  APB domain  s j -ze  can be  accounted  fo r  bya  m o d i f i e d  e q u a t i o n  f o r  C o t t r e l l ' s  d o m a i n  s t r e n g t h e n i n g .The ac t iva t lon  energy  deduced f rom the  k ine t ic  s tud ies  o fAPB domain  growth  a t  severa l  tempera tures  is  about  the  same ast h e  a c t i v a t i o n  e n e r g y  f o r  d i f f u s i o n  o f  Z n  o r  N i  i n  t h e  a l l o yC u " N i Z n .  T h e r e f o r e ,  A P B  d o m a i n  g r o w t h  i s  p r o b a b l y  a  d i f f u s i o nzo o n l - r a l  I e d  n r n c c g g .The order -d isorder  t rans format ion  in  CurNiZn shou ld  be  af i r s t  o r d e r  p r o c e s s  a c c o r d i n g  t o  t h e o r e t i c a l  p r e d i c t i o n s ,  w h i c his  conf i rmed by  the  measurement  o f  the  quas i -b inary  c ross-s e c t i o n  C u - ^ N i -  ^  Z n  .5 U  5 U - X  XThe va lue  o f  the  APB energy  ob ta ined f rom the  conf igura t iono f  s u p e r l a t t i c e  d i s l o c a t i o n s  i s  i n  a g r e e m e n t  w i t h  t h e o r e t i c a ln r p r l i c l - i n n q  f o r  t h i s  a l  l o v -  T h c  A p R  o n e r o \ /  d p d r r c c d  f r O m  t h e  c o n -y t  v s r ef i g u r a t i o n  o f  s u p e r l a t t j - c e  d i s l o c a t i o n  d i p o l e s  i s  n o t  r e l i a b l e .I ts  va lue  is  about  th ree  t imes smal le r  than the  va lue  ob ta i -nedf r o m  t h e  s u n e r  I  e  t t i - c e  d i s l o c a t i o n s  .The s tack ing  fau l t  energy  has  been ca lcu la ted  f rom the  d imen-s ions  o f  ex tended d is loca t ion  nodes by  app ly ing  severa l  theore t i -ca l  mode ls .  These mode ls  a re  sub iec ted  to  a  tes t  o f  i -n te rna lc o n s  i s  t e n c y .

Order-disorder transitions in ternary alloys

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Order-disorder transitions in ternary alloys

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