21386982 note chp 2 material science 281 uitm em110

8/13/2019 21386982 Note Chp 2 Material Science 281 Uitm Em110

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MEC281 : MATERIALS SCIENCE

CHAPTER 2 :

PHASE DIAGRAM

Rasdi bin DeramanJabatan Kejuruteraan Mekanikal

UiTM Pulau Pinang


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SOLIDIFICATION OF PURE METALS &ALLOYS

The solidii!"#io$ o %e#"ls "$d #hei "llo's is"$ i%(o#"$# i$d)s#i"l (o!ess*

No# o$l' do s#)!#)e "llo's s#"# +i#h #he

!"s#i$, o i$,o#s o (o!essi$, i$#oei$o!i$, -"s o s#)!#)"l sh"(e. -)# +he$" %e#"l is +elded " s%"ll (o#io$ o %e#"l $e"#he +eld %el#s "$d esolidiies*

PHASE DIAGRAM


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A#e (o)i$, i$#o #he %old. #he %ol#e$

%e#"ls/"llo's !ool "$d solidi'*

Solidii!"#io$ is #he %os# i%(o#"$# (h"se

#"$so%"#io$ -e!")se %os# o %e#"ls/"llo's

)$de,o #his #"$so%"#io$ -eoe -e!o%i$,

)se)l (od)!#s*

Solidii!"#io$ i$0ol0e li)idsolid (h"se

#"$so%"#io$. e*, : !"s#i$, (o!ess*

The solidii!"#io$ (o!ess dies de(e$di$,

o$ +he#he #he %e#"l is " ()e ele%e$# o "$

"llo'*


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I$ ,e$e"l #he solidii!"#io$ o %e#"ls o "llo's !"$-e di0ided i$#o #he ollo+i$, s#e(s:

i3 The o%"#io$ o $)!lei i$ #he %el#4$)!le"#io$3

ii3 The ,o+#h o $)!lei i$#o !'s#"liii3 The o%"#io$ o " ,"i$ s#)!#)e

Liquid

Nuclei

Liquid

Grain

Grain boundaries

Irregular grain

"3 -3 !3

Solidii!"#io$ Po!ess


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*rmatin % the grain +nes

A# #he +"lls o #he %old. #he %ol#e$ %e#"ls/"llo's

!ools "(idl'* As " es)l#. #he !"s#i$, de0elo(s s%"lle)i"5ed ,"i$sd)e #o #he l",e #e%(* ,"die$# "# #he

s)"!e*

As !ooli$, !o$#i$)es. #he ,"i$s ,o+ i$ #he die!#io$

o((osi#e #o #he he"# lo+ +hee #he ,"i$s ,o+

i$+"dl' "s $eedles is 6$o+$ "s !ol)%$" ,"i$s*


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For pure metals, columnar grains will stop to

grow until complete solidification has

occurred.

For alloys, further cooling of the molten alloy

will cause formation of l",e e)i"5ed,"i$s. showing segregation of alloying

components in the center of casting due to

the imbalance in composition between themetal that has solidified and the remaining

molten metal.


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Figure : chematic illustration of two cast structures of metals solidified in a square mold:

!a" pure metals# !b" alloys

-3"3

S%"ll

e)i"5ed

7o$e

Col)%$"

,"i$s

L",e

e)i"5ed

7o$e


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$ost metals are combined to form

alloy in order to impart specific

characteristic.

%n "llo' is a combination of two or

more elements !added impurity

atoms", at least one of which is a

metal.

&he addition of impurity atoms to a

metal will result in the formation of a

solid sol)#io$which composed of

sol0e$#!host atoms" and sol)#e!alloying elements".

'.g : teel(cast iron !iron base

alloys", bron)e(brass !copper base

alloys", %l alloys, Ni base alloys, $gbase alloys, &i alloys.

METALLIC SOLID SOLUTION


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T+o #'(es o solid sol)#io$s:

i* I$#es#i#i"l Solid Sol)#io$

ii* S)-s#i#)#io$"l Solid Sol)#io$

Mos# e$,i$eei$, %e#"ls "e !o%-i$ed

+i#h o#he %e#"ls o $o$%e#"ls #o (o0ide

i$!e"sed s#e$,#h. hi,he !oosio$

esis#"$!e o #he desied (o(e#ies*

The si%(les# #'(e o "llo' is " %i5#)e o#+o sol)#io$ +hi!h is !o$sis#s o #+o o

%oe ele%e$#s "#o%i!"ll' dis(esed i$ "

si$,le (h"se s#)!#)e*

TYPES OF SOLI SOL!TIO"


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E5"%(les o "#o%s #h"# !"$

o% I$#es#i#i"l Solid

Sol)#io$s d)e #o #hei s%"ll

si7e "e h'do,e$. !"-o$.

$i#o,e$. "$d o5',e$*

A solid sol)#io$ o%ed i$ +hi!h sol)#e "#o%s!"$ e$#e #he holes i$ #he sol0e$#"#o% l"##i!e*

The sol)#e "#o%s i# i$#o #he s("!es -e#+ee$

#he sol0e$# o ("e$# "#o%s*

I$#es#i#i"l Solid Sol)#io$s


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The l"##i!e dis#o#io$ !e"#es " s#"i$ "lo$, #he sli( (l"$es "$d ,"i$s o #he %"#ei"l.

+hi!h es)l#s i$ #he i$!e"se o s#e$,#h "$d h"d$ess -e!")se i# %"6es "#o%-'

"#o% sli( "lo$, #hose (l"$es %oe dii!)l#*

i3 S)-s#i#)#io$"l solid sol)#io$ ii3 I$#es#i#i"l solid sol)#io$

Fi,)e : This is " s!he%"#i! ill)s#"#i$, ho+ #he l"##i!e is s#"i$ed -' #he "ddi#io$ o

s)-s#i#)#io$"l "$d i$#es#i#i"l sol)#e* No#i!e #he s#"i$ i$ #he l"##i!e #h"# #he sol)#e "#o%s

!")se*


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A solid sol)#io$ i$ +hi!h sol)#e "#o%s o o$e ele%e$#s

!"$ e(l"!e #hose o sol0e$# "#o%s o "$o#he ele%e$#*

I# !"$ -e o%ed -' #+o ele%e$#s sol)#e "#o%s !"$

s)-s#i#)#e o ("e$# sol0e$# "#o%s i$ " !'s#"l l"##i!e*

The !'s#"l s#)!#)e o #he sol0e$# is )$!h"$,ed. -)##he l"##i!e %"' -e dis#o#ed -' #he (ese$# o #he

sol)#e "#o%s*

Fo e5"%(le. i$ " C)Ni solid sol)#io$ #he C) "#o%s

!"$ e(l"!e #he Ni "#o%s i$ #he solid sol)#io$ !'s#"ll"##i!e*

2*2*2 S)-s#i#)#io$"l Solid Sol)#io$s


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This !o$i,)"#io$ !"$ -e #e$d #o o!!) +he$ #he "#o%s

do $o# die ,e"#l' i$ si7e "$d %)s# -e )i#e si%il" :

Less #h"$ "-o)# 19 diee$!e i$ "#o%i! "dii

The s"%e !'s#"l s#)!#)e

Si%il" ele!#o$e,"#i0i#' 4#he "-ili#' o #he "#o% #o

"##"!# "$ ele!#o$3

The s"%e 0"le$!e*


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2* SOLUTION

;he$ #+o !o%(o$e$#s !o%-i$ed #he' !"$ ei#he e%"i$

se(""#e e$#i#ies o !o%-i$e #o o% " si$,le (h"se +hi!h

is eeed #o "s " sol)#io$* De,ee #o +hi!h #he #+o!o%(o$e$#s %i5 is eeed #o "s #he sol)-ili#'*

Sol)#io$s !"$ "lso o!!) i$ #he solid s#"#e "$d +i#h #he

s"%e "$,e o sol)-ili#' "s des!i-ed o li)ids*

E5"%(les: C) "$d Ni "e completelysol)-le


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A (h"se di","% is " ,"(hi!"l e(ese$#"#io$ o #he (h"ses

(ese$#. !o%(osi#io$. "$d #e%(e"#)e "# e)ili-i)% o #he

s#)!#)e o "$ "llo' o !e"%i!s i$ +hi!h #he (h"ses "es#"-le* Ph"se Di","% %os# i%(o#"$# #ools "0"il"-le #o

%"#ei"ls s!ie$#is# "$d e$,i$ees*

2*>*1 ?i$"' Ph"se Di","%s

A -i$"' (h"se di","%s !o$sis# o #+o ele%e$#s i$

o$e "llo'* Thee "e #hee #'(e o (h"se di","%s:

i* Co%(le#e Solid Sol)#io$

ii* No Solid Sol)#io$

iii* Li%i#ed Solid Sol)#io$

2*> THE PHASE DIAGRAMS


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2*>*2 ?i$"' Ph"se Di","%s o Co%(le#e Solid Sol)#io$

This (h"se di","% sho+s "$ isomorphous@s's#e% i$

+hi!h o$l' o$e solid (h"se o%s* @Isomorphicity %e"$s

h"0i$, s"%e !'s#"l s#)!#)e o !o%(le#e solid sol)-li#'

o "ll !o%(osi#io$*

The "llo' is solid o "ll

!o%(osi#io$ "# #e%(e"#)e

-elo+ T%.A

The "llo' is li)id o "ll

!o%(osi#io$ "# #e%(e"#)e

"-o0e T%.?

li)id)s li$e

Solid)s li$e

T%.A

T%.?


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The ele%e$#s "e dissi%il" #h"# #hei sol)-ili#' i$ o#he

is $e"l' !"$ $e,li,i-le*

Li#uidus line

Solidus line

Temperature

$omposition

Eutectictemperature

Eutectic point

L

A % &

A % L & % L

A &

2*>* ?i$"' Ph"se Di","%s o No Solid Sol)#io$

The i,)e -elo+ sho+s ele%e$# A "$d ? !"$$o#

dissol0es +i#h e"!h o#he* The ele%e$#s "e o$l'

!o%(le#el' sol)-le i$ #he li)id s#"#e -)# !o%(le#el'

i$sol)-le i$ #he solid s#"#e*


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The ele%e$#s "e dissi%il" #h"# #hei sol)-ili#' i$ o#he is

$e"l' !"$ $e,li,i-le*

Li#uidus line

Solidusline

Temperature

$omposition

Eutectic

temperature

Eutectic point

Li#uid, L

% L % L

A &

2*>*> ?i$"' Ph"se Di","%s o Li%i#ed Solid Sol)#io$

Solidusline

Sol'uslineSol'us

line

+

The i,)e -elo+ sho+s ele%e$# A "$d ? !"$$o# dissol0es

+i#h e"!h o#he* The ele%e$#s "e o$l' !o%(le#el' sol)-le i$

#he li)id s#"#e -)# !o%(le#el' i$sol)-le i$ #he solid s#"#e*


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2* THE GI??S PHASE RULE

Ph"se di","% des!i-e #he%od'$"%i! e)ili-i)%

!o$di#io$* N)%-e o (h"ses i$ e)ili-i)% li%i#ed -'

#he%od'$"%i!s*

This is des!i-ed -' Gi--s (h"se )le:

" , % - # , n

p = number of phases presentf = number of degrees of freedom

(s#"#e 0"i"-les : Te%(e"#)e. Pess)e

"$d !o%(osi#io$3

c = no. of components

n = no. of noncompositional variables

4$ 1 o "llo'/!e"%i!. $ 2 o !o$de$s"#e3


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E5"%(lesI!e+"#es#e"% : dis#i$!# (h"ses

gas

slidli$uid

Tem"erature

Pres

sur

e

T( T) T*


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slid

li$uid

Tem"erature

Pres

sur

e

One phase two degrees of freedom

P(

P)

T( T) T*


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slidli$ui

d

Tem"erature

Pres

sur

e

Two phases one degree of freedom

T( T)

P(P)


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slidli$uid

Tem"erature

Pres

sur

e

Three phases zero degree offreedom

P.

T.

;he$ #he de,ee o eedo% is e)"l #o 7eo. i# is !"lled

i$0"i"$# (oi$#*

gas


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Ph"se )le o -i$"' s's#e% . !2 4A "$d ?3

F P

A si$,le (h"se . P1 . F2

!o%(osi#io$ "$d #e%(e"#)e !"$ -e !h"$,ed

i$de(e$de$#l'

T+o(h"se %i5#)e F1

* "# " ,i0e$ #e%(. #he !o%(osi#io$ o #he li)id "$d solid

is i5ed . ,i0e$ -' #he li)id)s "$d solid)s li$e


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2*B INTERPRETATION OF PHASE DIAGRAM ?Y USING

LEER RULES METHOD

A (h"se di","% ,i0es #he ollo+i$, i$o%"#io$:

The (h"se (ese$# 4solids "$d li)ids o !o%-i$"#io$s3

The !o%(osi#io$ 4!he%i!"l %"6e)(3 o #hese (h"ses

The "%o)$# o e"!h (h"se

2*B*1 The (h"se (ese$#

O$e )s# lo!"#es #he #e%(e"#)e = !o%(osi#io$ (oi$#

o$ #he di","% "$d $o#es #he (h"se4s3 +i#h +hi!h #he

!oes(o$di$, (h"se ield is l"-eled*


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2*B*2 The !o%(osi#io$

i* D"+ #he #ie li$e "!oss #he #+o(h"se e,io$ "# #he#e%(* o #he "llo'*

ii* The i$#ese!#io$s o #he #ie li$e & (h"se -o)$d"ies o$

ei#he side "e $o#ed*

iii* D"+ #he (e(e$di!)l" li$e o% #hese i$#ese!#io$s #o#he hoi7o$#"l !o%(osi#io$ "5is.


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2*B* De#e%i$"#io$ o Ph"se A%o)$#

Te%(e"#)e 12 C

Co%(osi#io$ +#9NiB +# 9 Ni

Ph"ses (ese$# Li)id

M"ss "!#io$ o . ; "$d

M"ss "!#io$ o Li)id. ;L

L

o

L

L

CC

CCW

SR

SW

=

+

=

The el"#i0e "%o)$#s o #he (h"ses (ese$# "# e)ili-i)%

!"$ -e de#e%i$ed -' )si$, Le0e R)le %e#hod*


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E5"%(le: ?"sed o$ #he di","% -elo+. de#e%i$e #he (h"se (ese$#.

#he !he%i!"l !o%(osi#io$ "$d el"#i0e (h"se "%o)$# "# #he

!o%(osi#io$ "$d #e%(e"#)e +#9 Ni "$d 1 Ces(e!#i0el'*

Solution:


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E5"%(le:

?"sed o$ #he di","% -elo+. de#e%i$e #he (h"se (ese$#.

#he !he%i!"l !o%(osi#io$ "$d el"#i0e (h"se "%o)$# "# #he

!o%(o* "$d #e%(* +#9 S$ "$d 2 C es(e!#i0el'*

Solution:


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E5"%(le: ?"sed o$ #he di","% -elo+. de#e%i$e #he (h"se

(ese$#. #he !he%i!"l !o%(osi#io$ "$d el"#i0e (h"se

"%o)$# "# #he e)#e!#i! (oi$# "$d sli,h#l' -elo+ e)#e!#i!#e%(e"#)e*

Solution:


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+'

E)#e!#i! #e%(* 4TE3 :

No li)id -elo+ TE

"$d o% 2 diee$#

solid (h"ses*

E)#e!#i! #e%(* 4TE3

"*6*"* #i(le (oi$#*

E)#e!#i! !o$!e$#"#io$ 4CE3 :

Mi$* %el#i$, #e%(* !o%(osi#io$ 4CE3Fi,)e : Co((esil0e (h"se di","%


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Gradual solidification of the -% / -0 composition

Mi!os#)!#)"l de0elo(%e$# d)i$, slo+ !ooli$,


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Fi,)e : P-S$ s's#e%


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Cooling curve )se)l #ools o s#)d'i$, #he

solidii!"#io$ (o!ess*

I$ solidii!"#io$ o "llo'ed %e#"ls. #he #e%(* o(h"se !h"$,es +ill -e diee$# o e0e'!o%(osi#io$ (because alloy consists of 2 or more

metals).

The #e%(* & !o%(* o (h"se !h"$,es !"$ -e,"(hed so #h"# "ll (ossi-le !o%-i$"#io$ o #+o()e %e#"ls "e e(ese$#ed*

This +ill (od)!e " ,"(h 6$o+$ "s PHS!"I#$%+hi!h sho+s #he el"#io$shi( "%o$,#e%(*. !o%(* & (h"ses (ese$# i$ "llo' s's#e%*

COO/I01 CURVE DI21R2M

COO/I01 CURVE *OR


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*r "ure metal3 the#ling #ur(es sh!hri+ntal thermalarrest at their%ree+es "ints'

Di%%erent #m"sitin!ill gi(e di%%erent#ling #ur(es'

The sl"e #hanges at/.45. et#'3 are#rres"nd t theli$uidus and slidus'

L1

S1

Freezingzone

COO/I01 CURVE *ORISOMORPHOUSBINARY

DI21R2M1


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e)ili-i)% (h"se di","%

A -i$"' iso%o(ho)s !ooli$, !)0es


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Li)id Solid

Li)id

Solid

A ? C D

$OOLI"+ $!-E FO EUTECTICBINARYIA+A.

Solid

Li)id

2 8 ARIOUS TYPE OF ALLOY TRANSFORMATIONS


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2*8*1 E)#e!#i!e T"$so%"#io$s

L +cooling

The e)#e!#i! #"$so%"#io$ o!!)s "# 18oC "# " !o%(* o B19 S$*

+

I$ #he e)#e!#i! e"!#io$ #he si$,le li)id (h"se #"$so%s

si%)l#"$eo)sl' i$#o #he #+o solid (h"ses o% "# #he e)#e!#i!

#e%(e"#)e* The e)#e!#i! e"!#io$ !"$ -e +i##e$ "s.

2*8 ARIOUS TYPE OF ALLOY TRANSFORMATIONS

FOR ?INARY PHASE DIAGRAMS


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11oC

2*8*2 Pei#e!#i! "llo' #"$so%"#io$s

I$ #he (ei#e!#i! e"!#io$ " li)id (h"se e"!#s +i#h "

solid (h"se #o o% " $e+ "$d diee$# solid (h"se*

The (ei#e!#i! e"!#io$ !"$ -e +i##e$ "s.Li)id. L

Fo e5"%(le.

L (5.4% Ni) + (4.0% Ni) (4.3% Ni) cooling


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2*8* Mo$o#e!#i! #"$so%"#io$

/. , /

6

The %o$o#e!#i! e"!#io$ o!!)s +hee "# " s(e!ii! #e%(*

#he li)id sol)#io$ o !o%(osi#io$ L1#"$so%s i$#o " solid

(h"se "$d " se!o$d li)id o !o%(osi#io$ L2+hi!h isdiee$# o% L

1* The e)"#io$ e"ds:

cooling

The %o$o#e!#i!

#"$so%"#io$ o!!)s

"# oC "# " !o%(*o

B9 P-* Fo% oC

do+$. (o!6e#s o le"di!h %el# "e e$#"((ed

i$ #he solid C) "l(h"

(h"se*

2 8 > E)#e!#oid #"$so%"#io$


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The e)#e!#oid e"!#io$ is si%il" #o #he e)#e!#i! e"!#io$ i$ #h"#

o$e (h"se de!o%(ose i$#o #+o (h"ses )(o$ !ooli$,*

A e)#e!#oid e"!#io$ +hee #he si$,le solid (h"se #"$so%s i$#o

solid (h"ses h"0i$, diee$# !o%(osi#io$s o% #he (h"se*

The e)#e!#i! e"!#io$ !"$ -e +i##e$ "s.

2*8*> E)#e!#oid #"$so%"#io$

+ cooling

A i$ (ei#e!#oid e"!#io$ #he #+o solid (h"ses #"$so% i$#o #he

si$,le solid (h"se* The (ei#e!#oid e"!#io$ !"$ -e +i##e$ "s.

2*8* Pei#e!#oid #"$so%"#io$

+ cooling

2 8 B Mo$o#e!#oid #"$so%"#io$


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2*8*B Mo$o#e!#oid #"$so%"#io$

+ 21cooling

The %o$o#e!#oid e"!#io$ o!!)s +hee "# " s(e!ii! #e%(*

#he solid sol)#io$ o !o%(osi#io$ #"$so%s i$#o #he

#+o solid (h"ses * The e)"#io$ e"ds:

1

The #"$so%"#io$ o " E)#e!#i!. Pei#e!#i! "$d Mo$o#e!#i!

is !o$side "s #he #"$so%"#io$ o% li&uid#o solid phase.

;hile #he #"$so%"#io$ o " E)#e!#oid. Pei#e!#oid "$d

Mo$o#e!#oid is !o$side "s #he #"$so%"#io$ o% solid

#o solid phase.

2 INARIANT REACTIONS


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2* INARIANT REACTIONS

J I$0"i"$# e"!#io$s "e o)$d i$(h"se di","%s o %"$' -i$"'

"llo's* A$ "llo' %"' h"0e o$l'

o$e i$0"i"$# e"!#io$ 4 e*,* P-

S$3 o h"0e %"$' i$0"i"$#

e"!#io$s de(e$di$, o$!o$!e$#"#io$ "$d #e%(e"#)e

4see e$,i$eei$, "llo's3*

I$0"i"$# e"!#io$s "e "l+"'s

de#e%i$ed i$ " $ei,h-ohood o#he #i(le (oi$# #h"# (i$s #he

i$0"i"$# e"!#io$* A!!odi$, #o

Gi--s (h"se )le #hee is 7eo

de,ees o eedo% "# #hese

e"!#io$ (oi$#s*

;he$ #he de,ee o eedo% is e)"l #o 7eo. #he e"!#io$ is

!"lled i$0"i"$# e"!#io$*


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'1%$2L'

Find the peritectic and eutectoid reactions in the +u*3n

system4


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TUTORI2/

&ismuth /melting point )0(1$2 and cadmium /meltingpoint *)(1$2 are assumed to be completel3 soluble inthe li#uid state and completel3 insoluble in solid

state4 The3 form a eutectic at (551$ containing 56 7cadmium4

ra8 the e#uilibrium diagram to scale on a piece ofgraph paper labeling all points, lines and areas4

For an allo3 containing 067 cadmium,

etermine the temperature of initial and finalsolidification4

etermine the chemical composition and relati'eamounts of phases present at a temperature of)661$4

S9etch the microstructure at room temperature4 ra8 the cooling cur'e4

OCT 6778


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OCT 6778The cooling cur'es obtained 8hen t8o puremetals and se'eral of their allo3s 8ere cooled

from the li#uid phase are sho8n in figurebelo84


48/74

a2ra8 the phase diagram for the allo3 s3stemto scale on a piece of graph paper and label

all points, lines and areas4b2 For an allo3 containing 56 8t7A,

determine the li#uidus temperature, solidustemperature and freeing range of the allo34

c2$onsider an allo3 containing (6 8t7A4uring solidification, determine compositionof the first solid to form4

d2For an allo3 containing 068t7 A, determinethe chemical composition and relati'eamount of phases present at ;661$4

T bl . 7 h t t % th


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Table .'7 sh!s tem"eratures % thebeginning and ending % the slidi%i#atin%r 1ermanium45ili#n s&stem' Cnstru#t

a "hase diagram t s#ale n a "ie#e %gra"h "a"er labeling all "ints3 lines andareas'


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iii' Des#ribe the slidi%i#atin "r#ess% a 87!t95i

and determine its #hemi#al#m"sitins and relati(e amunts% "hases "resent at a tem"erature% .6:7;C'

iv. Draw the cooling curve for the 40wt%Si alloy.

v. Descrie the soli!ification "rocess.

#or an alloy containing 40wt%$e which is coole!

fro li&ui! "hase to roo te"erature' !eterine

i. the co"osition of the first li&ui! soli!ifie!.

ii. the co"osition of the last li&ui! soli!ifie!.

M2R 6778


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M2R 6778A h3pothetical A


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OCT 677Cnt''?

3poeutectoid plain carbon steel:If a sampleof 6457 $ is heated up to >666$, it gets

austenitied, 4 Further cooling gi'es rise to G and pearlite46earlite

5l! Cling % Plain Carbn 5teel


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#2

g>Cnt''?

&"ereute#tid "lain #arbn steel=I% a.'69 C sam"le is heated u" t :77C and

held %r su%%i#ient time3 it entirel& getsausteniti+ed'

*urther #ling results results in

eute#tid #ementiteand "earlite'

* ti % lit


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#'

*rmatin % "earlite T!4dimensinal mr"hlg& % "earlite3 a""arentl&

#nsisting % alternating la&ers % #ementite and %errite'

& 7hree!iensional analogy to theor"hology of "earlite' i.e. thecaage re"resents a single crystal

of "earlite' an! the water in theuc8et the single crystal of ferrite.

9 h f i l h f


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#"

Eg 6: S9etch of microstructural changes for asteel containing 645 7 $ as it is cooled from8ithin the austenite phase region to belo8eutectoid temp4

5O/UTIO0=

/Ans: pearlite =(72


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#!

E(lutin %Mi#rstru#ture

Eu#te#tid

YPOE!TE$TOI STEEL


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##

/Fe


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#$

/Fe


68/74

#8


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car3on steel alloy containing 0' wt% C when cooled

4ust 3elow eutectoid temperature le5el etermine6

a) 7he relati5e amount of proeutectoid ferrite form.

3) 7he relati5e amount of eutectoid ferrite form.

c) (ketch the microstructure of item a) and 3)

respecti5ely

. )66=


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$0

.ar )66=

Jith the aid of a neat s9etch, describe the

microstructural changes 8hich ta9e place8hen a (4( 8t7 plain carbon steel is slo8l3cooled from the austenite region ust abo'ethe upper critical temperature line4

(ep 2001

car3on steel alloy containing 0! wt% C when cooled

from the austenite region crosses the ' line escri3ewith neat sketches the microstructural changes that take

place during the slow cooling of this steel from the

austenite region

ECample*


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$1

*4

A 64)=7 $ h3poeutectoid plain=61$ to a temp4 ust slightl3 belo80)01$4 $alculate:

/a2 the 8eight percent proeutectoid ferrite in the steel4

/b2 the 8eight percent eutectoid ferrite and 8eight percenteutectoid cementite in the steel4

00% C hypereutectoid plaincar3on steel is slowly

cooled from 009C to a temperature 4ust slightly a3o5e

$2$9C Calculate the weight percent proeutectoid

cementite and weight percent austenite present in the

steel:;ample "


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$2

ECample=4

What is the Car3on concentration of an ironcar3on alloyfor which the relati5e amount fraction) of total ferrite is

0"

21386982 note chp 2 material science 281 uitm em110

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