nucleation and crystalization in bulk metallic glasses

8/17/2019 Nucleation and Crystalization in Bulk Metallic Glasses

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NUCLEATION AND CRYSTALIZATION IN BULK METALLIC GLASSES

Ramsha KhanMECE 6364 – Phase Trans !rma"#!n #n Ma"er#a$s

A%r#$ &'(6

INTRODUCTION

N)*$ea"#!n #s +e #ne+ as "he !rma"#!n ! a ne, "herm!+-nam#* %hase #n a ma"er#a$. I"

*!)$+ e#"her /e h!m!0en!)s1 !r he"er!0ene!)s. 2e"er!0ene!)s n)*$ea"#!n !**)rs a" a s)r a*e

,#"h#n "he ma"er#a$ *a$$e+ "he n)*$ea"#!n s#"e1 ,h#*h *!)$+ /e a 0ra#n /!)n+ar- !r an #m%)r#"-.

hereas h!m!0en!)s n)*$ea"#!n !**)rs ,#"h!)" an- %re eren"#a$ n)*$ea"#!n s#"es1 an+ #s

"here !re s%!n"ane!)s an+ ran+!m.

A 0$ass #s an am!r%h!)s s!$#+1 ,h#*h means #" s n!n5*r-s"a$$#ne $# e a $#7)#+ /)" s"#$$ h!$+s

#"s sha%e $# e a s!$#+. G$ass #s )s)a$$- !rme+ ,hen -!) *!!$ a $#7)#+ ra%#+$-1 hen*e a8!#+#n0 "he

n)*$ea"#!n ! a *r-s"a$ s"r)*")re an+ an- )r"her *r-s"a$$#9a"#!n. Re*en"$- s*#en"#s"s ha8e !)n+ a

ne, *$ass ! ma"er#a$s *a$$e+ Me"a$$#* G$asses1 ,h#*h #s an am!r%h!)s s"r)*")re ! me"a$ a$$!-s.

The #rs" s-n"hes#s ! an am!r%h!)s %hase #n an A)5S# s-s"em ,as +!ne #n (:6' /- D),e9 a"

Ca$"e*h USA ;(


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Man- *$asses ! BMG ma"er#a$s ha8e n!, /een +e8e$!%e+1 ,#"h *r#"#*a$ *!!$#n0 ra"e !

as $!, as '.(' K>s !r "he P+ 4' C) 3' N#(' P&' a$$!-1 an+ sam%$e "h#* ness ! as $ar0e as ('*m. Ta/$e

( $#s"s s!me "-%#*a$ BMG am#$#es an+ "he -ear "he- ,ere +e8e$!%e+.

Table 1: Bulk metallic glasses and the year they were developed. Source [2]

NUCLEATION AND GROWTH OF CRYSTALS IN

A**!r+#n0 "! S Baner ee ;4< "hree s#")a"#!ns ! n)*$ea"#!n *an !**)r ,hen ,e )n+er*!!$ a me"a$

a$$!- s-s"em

(. N! n)*$ea"#!n ! *r-s"a$$#ne %hase *an /e a*h#e8e+ /- $aser 0$a9#n01 an+ "he 0$ass

%r!+)*e+ #s a/s!$)"e$- ree ! an- 7)en*he+5#n5n)*$e#.

BMG s-s"em YearsP+–C)–S# (:@4P"–N#–P (:@=A)–S#–Ge (:@=P+–N#–P (:F&M0–Ln–C) Ln $an"han#+e me"a$ (:FFLn–A$–TM TM 0r!)% "rans#"#!n me"a$ (:F:Zr–T#–A$–TM (::'T#–Zr–TM (::3Zr–T#–C)–N#–Be (::3

N+ Pr –A$–He–C! (::4Zr– N/1 P+ –A$–TM (::=C)–Zr–N#–T# (::=He– N/1 M! – A$1 Ga – P1 C1 B1 S#1 Ge (::=P+–C) He –N#–P (::6C!– A$1 Ga – P1 B1 S# (::6He– Zr1 2 1 N/ –B (::6C!–He– Zr1 2 1 N/ –B (::6N#– Zr1 2 1 N/ – Cr1 M! –B (::6T#–N#–C)–Sn (::FLa–A$–N#–C)–C! (::FN#–N/ (:::

N#– N/1 Cr1 M! – P1 B (:::Zr5/ase+ 0$ass- *!m%!s#"es (:::Zr–N/–C)–He–Be &'''He–Mn–M!–Cr–C–B &''&N#–N/– Sn1 T# &''3Pr N+ – C)1 N# –A$ &''3


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&. L#m#"e+ n)*$ea"#!n ! *r-s"a$s /)" n! 0r!,"h *an /e a*h#e8e+ /- me$" s%#nn#n0 me"h!+1

an+ 0$ass has s!me 7)en*he+5#n5n)*$e#1 ,here "he n)*$ea"#!n ra"e +e%en+s !n "he ra"e

! *!!$#n0.

3. N)*$ea"#!n ! a $#m#"e+ n)m/er ! *r-s"a$s an+ "he#r s)/s"an"#a$ 0r!,"h "he me"a$ 0$ass

has s!me *r-s"a$$#ne r#//!ns.

igure 1: !omparison o" critical cooling rate and reduced glass transition temperature "or B#$% silicate glasses and conventionalmetallic glasses. Source [2] & [']

THERMODYNAMIC AND KINETIC ASPECT OF GLASS FORMATION AND CRYSTALLIZATION

S!me "erms "ha" nee+ "! /e +e #ne+ !r )n+ers"an+#n0 "he G$ass !rm#n0 a/#$#"- !r GHA

! me"a$ a$$!-s

• T0 #s 0$ass "rans#"#!n "em%era")re.

• Tm #s me$"#n0 "em%era")re1 !r "he $#7)#+#s $#ne "em%era")re !r a$$!-s• Tr0 T0>Tm1 ,h#*h #s "he ra"#! ! 0$ass "! me$"#n0 "em%era")re #s +e #ne+ as re+)*e+ 0$ass

"rans#"#!n "em%era")re. 2#0her T r0 8a$)es means /e""er GHA.


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Three em%#r#*a$ r)$es ,ere s)mmar#9e+ /- In!)e #n ;3< as !$$!,s

(. GHA G$ass !rm#n0 a/#$#"- #n BMGs "en+s "! #n*rease /- #n*reas#n0 "he n)m/er !

e$emen"s #n "he s-s"em /e*a)se "he *!m%e"#n0 *r-s"a$$#ne %hases ,h#*h ma- !rm

#n*reases ,#"h #n*rease+ *!m%!nen"s1 an+ a*")a$$- +es"a/#$#9es "he s-s"em.

&. T! ha8e e$emen"s ,#"h 8ar-#n0 a"!m#* s#9e1 ha8#n0 m!re "han a (& s#9e ra"#!.

3. 2a8#n0 ne0a"#8e hea"s ! m#?#n0 8a$)es !r "he "hree ma#n *!ns"#")en" e$emen"s.

Ass)m#n0 s"ea+- s"a"e n)*$ea"#!n1 "he n)*$ea"#!n ra"e #s 0#8en /-

= −∆∗ ( .1)

here #s "he B!$"9mann s *!ns"an"1 T #s "he a/s!$)"e "em%era")re1 A #s a *!ns"an"1 D #s+#s*)rs#8#"- an+ ∆∗#s "he a*"#8a"#!n ener0- !r "he !rma"#!n ! a s"a/$e n)*$e#.

∆∗ = 163(∆) ( .2) here J #s "he #n"er a*#a$ ener0- /e",een "he n)*$e# an+ $#7)#+ %hase1 an+ ∆ #s "he

ree5ener0- +# eren*e /e",een "he $#7)#+ s"a"e an+ "he *r-s"a$$#ne s"a"e.

∆ ( ) = ∆! −∆"! # −$ ∆%&( )' $ ∆%&( ) '*

( .3)*

here ∆! #s en"ha$%- ! )s#!n a" #1∆"! #s "he en"r!%- ! )s#!n a" #1 ∆%&( ) #s+e$"a ! "he s%e*# #* hea" *a%a*#"-1 an+# #s "he "em%era")re a" ,h#*h "he *r-s"a$ an+ $#7)#+ are#n e7)#$#/r#)m.

Sma$$er 8a$)es ! ∆ a8!r h#0h GHA. A sma$$er en"ha$%- an+ h#0her en"r!%- ! )s#!nma es ∆ sma$$er. In*reas#n0 "he n)m/er ! a$$!- *!m%!nen"s #n "he BMG #n*reases "he ∆"! "erm1 an+ ha8#n0 a 8ar#a"#!n ! a"!m#* s#9es *a)ses a +enser a"!m#* %a* #n0 ! "he a"!ms #n "he

$#7)#+ s"a"e ,h#*h #n ")rn res)$"s #n a $!,er en"ha$%- ∆!. 2en*e In!)e s em%#r#*a$ r)$es !r#n*rease+ 0$ass !rm#n0 a/#$#"- #n me"a$$#* 0$asses are seen "! h!$+ "r)e !r "he a/!8e e7)a"#!ns.


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ZIRCONIUM-BASED METALLIC GLASSES

In #0)re & "he ree ener0- +# eren*e ∆+ !r Zr 33 an+ N# 6@ #s $!,er "han "ha" !r Zr&4 an+ N# @6 . Th#s sh!,s "ha" s)%er5*!!$#n0 ! 33 Zr a$$!- ,#$$ ha8e a h#0her am!r%h!)s

"rans !rma"#!n as *!m%are+ "! Zr &4 . Th#s !/ser8a"#!n #s a$s! *!n #rme+ /- "he T5T5T"em%era")re1 "#me1 "rans !rma"#!n *)r8e #n #0)re 3. e see "ha" "he n!se ! "he Zr 33 a$$!-

#s )r"her !)" !n "he "#me s*a$e1 ,h#*h means "ha" a s$!,er *!!$#n0 ra"e ,#$$ s) #*e !r an

am!r%h!)s "rans !rma"#!n as *!m%are+ "! Zr &4 "ha" has a m)*h as"er *!!$#n0 ra"e. An+ ,e

ha8e +#s*)sse+ ear$#er h!, s$!,er *!!$#n0 ra"es res)$" #n a /e""er am!r%h!)s 0$ass ma"er#a$1 as

n! n)*$ea"#!n !**)rs.

CONCLUSION

BMG ma"er#a$s ha8e a h#0h %!"en"#a$ !r /e#n0 )se+ #n man- a%%$#*a"#!ns s)*h as +#e

ma"er#a$s P+5C)5N#5P 1 s%!r"#n0 e7)#%men" ZrT#C)N#Be an+ ZrT#N#C) 1 e$e*"r!+e ma"er#a$s

P+C)S#P !r He5/ase+ BMG s !r s! " ma0ne"#* a%%$#*a"#!ns. ;&< BMG ma"er#a$s ,#$$ /e*!me m!re

s#0n# #*an" as )r"her resear*h an+ +e8e$!%men" #s *!n+)*"e+ !n !r "h#s *$ass ! ma"er#a$s.

igure 2: ree energy diagram o" li(uid phase in )r*+i system. Source [,]

igure ': Temperature time*trans"ormation curve "or )r*+isystem. Source [,]


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References

;(< K$emen"1 .1 #$$ens1 R. 2.1 D),e91 P. (:6'1 ': . N!n5*r-s"a$$#ne S"r)*")re #n S!$#+# #e+ G!$+5S#$#*!n A$$!-s.+ature% 1- 4@4' 1 F6:5F@'.

;&< .2. an01 C. D. &''41 Ma- (' . B)$ me"a$$#* 0$asses. #aterials Science and /ngineering% 0 ,, 1 4=5F:.

;3< In!)e1 A. &''' . STABILIZATION OH METALLIC SUPERCOOLED LI UID AND BULK AMORP2OUS ALLOYS. cta#ater% ,- 1 &@:53'6.

;4< G.K. De-1 S. B. (::&1 De*em/er . Ra%#+ s!$#+# #*a"#!n ! 9#r*!n#)m5/ase+ a$$!-s. Bulletin o" #aterials Science%1 6 1 =435==6.

nucleation and crystalization in bulk metallic glasses

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