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    5.1 DEFINITIONS AND BASIC CONCEPTS

    5.2 PHASE DIAGRAM

    5.3 MICROSTRUCTURE

    CHAPTER 5CHAPTER 5

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    har/jkbr/fkmp/2013 Materials Science 2

    What can you explain about the map shown in the above figure?

    Showing the region of sea (liquid phase) and land (solid phase) Showing boundaries lines between sea and land; and between countries (such

    as Malaysia !hailand "ndonesia etc#)

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    har/jkbr/fkmp/2013 Materials Science 3

    ISSUES TO ADDRESS...

    When we combine two elements... what equilibrium state do we get?

    In particular, if we specify...

    a composition (e.g., wt%Cu - wt%Ni), and a temperature (T)

    then...

    How many phases do we get?

    What is the composition of each phase?

    How much of each phase do we get?

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    har/jkbr/fkmp/2013 Materials Science 4

    Example of metal alloy system phase diagram (Figure 5.1), showing theregion of liquid phase, solid phase and the mixture of the two phases.

    Figure 5.1 : inary phase diagram

    ! " liquid phase

    and " solid phase

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    5.1 DEFINITIONS AND BASIC CONCEPTS

    It is funda!nta" t# at!$ia"s s%i!n%! and !n&in!!$in& t'at

    ($#(!$ti!s #f at!$ia"s $!f"!%ts t'!i$ i%$#st$u%tu$!.

    Mi%$#st$u%tu$!s a$! %#nt$#""!d )* t'! %#(#siti#n#f t'!at!$ia"s and '#+ it is($#%!ss!d.

    Manufa%tu$in& , s'a(in& - ass!)"in& !n&in!!$in&

    ($#du%t d!/i%!s - ($#/id!s t'! at!$ia"s ($#(!$ti!s

    $!0ui$!d.

    M#st at!$ia"s ($#%!ssin& in/#"/!s t'!$a" 'ist#$*.

    I(#$tant t# und!$stand '#+ ($#%!ssin& 'ist#$*

    (a$ti%u"a$"* t!(!$atu$! %#nt$#" i%$#st$u%tu$! and($#(!$ti!s.

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    har/jkbr/fkmp/2013 Materials Science 6

    S$M% %SS%&!"'( )%*"&"!"$&S +

    P'as! Dia&$aMAP #f at!$ia"s ('as!s#$ a dia&$a +it' t!(!$atu$! and %#(#siti#n as a4!s

    ($#/id! s#! funda!nta" n#+"!d&! #f +'at t'!!0ui"i)$iu st$u%tu$! #f a !ta""i% #$ %!$ai% a""#*.

    M!ta""i% A""#* a i4tu$! #f !ta"s +it' #t'!$ !ta"s #$ n#n6

    !ta"s.E4a("! 7 B$ass , a i4tu$! #f %#((!$ Cu and 8in% 9n

    C#(#n!nts t'! %'!i%a" !"!!nts #$ %#(#unds +'i%'

    a! u( a""#*s.E4a("! 7 in )$ass t'! ain %#(#n!nts a$! Cu and 9n.

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    har/jkbr/fkmp/2013 Materials Science 7

    Bina$* a""#* %#ntains t+# 2 %#(#n!nts.

    T!$na$* a""#* %#ntains t'$!! 3 %#(#n!nts.:ua$t!$na$* a""#* %#ntains f#u$ ; %#(#n!nts.

    P'as! a"" (a$ts #f an a""#* i%$#st$u%tu$! +'i%' 'as a'##&!n!#us at#i% st$u%tu$! and t'! sa! %#(#siti#n.

    F#$ !4a("!< in a )ina$* a""#* s#"id stat! t'!i%$#st$u%tu$! %an ta! #n! #f f#u$ f#$s=

    a a sin&"! s#"id s#"uti#n=

    ) t+# s!(a$at!d (u$! %#(#n!nts=

    % t+# s!(a$at!d s#"id s#"uti#ns=

    d %'!i%a" %#(#unds< t#&!t'!$ +it' s#"id s#"uti#n.

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    har/jkbr/fkmp/2013 Materials Science 8

    #olid solution" a solid in whi$h an element is %dissol&es' in another sothat it is homogeneously dispersed, at an atomi$ s$ale.

    A""#* a$! d!s%$i)!d )* statin& t'! %#(#n!nts and t'!i$

    %#n%!nt$ati#ns< in +!i&'t #$ at# >.

    T'! +!i&'t > #f %#(#n!nt A 7

    T'! at# #$ #" > #f %#(#n!nt A 7

    N#. #f #"s ? +!i&'t in &$as@at#i% #$ #"!%u"a$ +t in &$as@#"

    t in &$as ? N#. #f #"s 4 at#i% #$ #"!%u"a$ +t in &$as@#"

    %100componentsallofweight

    Acomponentofweight=

    A

    W

    %100componentsallofmols)(oratomsofnumber

    Acomponentofmols)(oratomsofnumber=

    A

    X

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    C#nstituti#n t'! %#nstituti#n #f an a""#* is d!s%$i)!d )* 7

    a t'! ('as!s ($!s!nt

    ) t'! +!i&'t f$a%ti#n #f !a%' ('as!

    % t'! %#(#siti#n #f !a%' ('as!

    E0ui"i)$iu %#nstituti#n t'!$! is n# fu$t'!$ t!nd!n%* f#$t'! %#nstituti#n #f a sa("! #f &i/!n %#(#siti#n t# %'an&!

    +it' ti! at a %#nstant t!(!$atu$! T and($!ssu$! (.

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    5.2 PHASE DIAGRAM

    P$#%!ssin& #f !n&in!!$in& at!$ia"s a"+a*s in/#"/!s at!$ia"sin "i0uid #$ s#"id stat!.

    In t'!s! stat!s< ($!ssu$! ( #n"* 'as a sa"" inf"u!n%! #n t'!!0ui"i)$iu %#nstituti#n< and %an )! n!&"!%t!d.

    In ('as! dia&$a< +! +i"" #n"* )! %#n%!$n!d +it' at!$ia"stat!s +'i%' a$! %#nt$#""!d )* t'! $!ainin& t+# stat!

    /a$ia)"!s 7 t!(!$atu$! and %#(#siti#n.

    T'! ('as! dia&$a #f t'! %#(#n!nts A and B is d!t!$in!dat a standa$d ($!ssu$! #f 1 at )* t'! t!(!$atu$! T and t'!%#(#siti#n B #$ B #$ A #$ A.

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    S#! #f t'! i(#$tant inf#$ati#n #)taina)"! f$# ('as!

    dia&$as is 7

    1. T# s'#+ +'at ('as!s a$! ($!s!nt at diff!$!nt

    %#(#siti#ns and t!(!$atu$!s und!$ s"#+ %##"in&!0ui"i)$iu %#nditi#ns.

    2. T# indi%at! t'! !0ui"i)$iu s#"id s#"u)i"it* #f #n!

    !"!!nt #$ %#(#und in an#t'!$.3. T# indi%at! t'! t!(!$atu$! at +'i%' an a""#* %##"!d

    und!$ !0ui"i)$iu %#nditi#ns sta$ts t# s#"idif* and t'!

    t!(!$atu$! $an&! #/!$ +'i%' s#"idifi%ati#n #%%u$s.

    ;. T# indi%at! t'! t!(!$atu$! at +'i%' diff!$!nt ('as!s

    sta$t t# !"t.

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    -

    Liquidus line

    Solidus lineSolidus line

    Solvus lineSolvus line

    *igure ,#- +!he 'g./u equilibrium system showing types of linesin the binary phase diagram#

    -rich solid () -rich solid ()

    '*(#!ut!%ti% '*(!$!ut!%ti%

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    har/jkbr/fkmp/2013 Materials Science 13

    Fi&u$! 5. s'#+s t'! t*(!s #f "in! in t'! ('as! dia&$a 7

    i0uidus "in! t'! ('as! )#unda$* +'i%' "iits t'! )#tt#

    #f t'! "i0uidfi!"d

    S#"idus "in! t'! "in! &i/in& t'! u((!$ "iit #f t'! sin&"!

    ('as! s#"id fi!"d.

    S#"/us "in! t'! "in! +'i%' s!(a$at!s t'! t+# ('as! fi!"d

    +it' t'! sin&"! ('as! s#"id fi!"d.

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    har/jkbr/fkmp/2013 Materials Science 14

    !01%S $* "&2'3"'&! 3%'/!"$&S +

    Eut!%t#id a ('as! t$ansf#$ati#n in +'i%' a s#"id ('as!t$ansf#$s #n %##"in& int# t+# s#"id ('as!s is#t'!$a""*.

    , -

    Eut!%ti% a ('as! t$ansf#$ati#n in +'i%' a"" t'! "i0uid ('as!t$ansf#$s #n %##"in& int# t+# s#"id ('as!s is#t'!$a""*.

    , -

    P!$it!%ti% a ('as! t$ansf#$ati#n in +'i%'< u(#n %##"in&< a"i0uid ('as! %#)in!s +it' a s#"id ('as! t# ($#du%! a n!+

    s#"id ('as!. - ,

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    har/jkbr/fkmp/2013 Materials Science 15

    ale 5.1 : ypes of hree*+hase n&ariant -ea$tions $$urring in inary

    +hase /iagrams

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    5.2.1 R!adin& a ('as! dia&$a

    A T'! %#nstituti#n (#int

    T'! stat! /a$ia)"!s< t!(!$atu$! and %#(#siti#n Sn and P)62

    +t> Sn a""#*s at 25C.

    'at d#!s t'! a""#* %#nsist #f in !a%' %as!

    P)6 +t> Sn 7 .

    P)62 +t> Sn 7 .

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    3. T'! a""#* %#$$!s(#ndin& initia""* t# t'! %#nstituti#n (#int 1 is%##"!d /!$* s"#+"* t# $## t!(!$atu$!.

    At +'i%' t!(!$atu$!s d# %'an&!s in t'! nu)!$ #$ t*(! #f('as!s #%%u$

    'at ('as!s a$! ($!s!nt at (#int 2.......

    'at ('as!s a$! ($!s!nt at (#int 3...

    ;. Sii"a$"*< t'! a""#* %#$$!s(#ndin& t# t'! %#nstituti#n (#int ;is %##"!d t# $## t!(!$atu$!. Id!ntif* t'! f#""#+in& 7

    Initia" %#(#siti#n t!(!$atu$! 7 ..

    Initia" ('as!s 7

    T!(!$atu$! at +'i%' %'an&! t'! ('as! #%%u$s 7

    Fina" ('as!s 7 .

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    B C#(#siti#n #f t'! ('as!s

    In a sin&"!6('as! $!&i#n< t'! ('as! %#(#siti#n anda""#* %#(#siti#n %#in%id!.

    In a t+#6('as! $!&i#n< t'! %#(#siti#ns #f t'! ('as!s

    a$! f#und at t'! !nds #f t'! is#t'!$a" "in! s(annin&

    t'! fi!"d t'$#u&' t'! %#nstituti#n (#int. T'is "in! is

    %a""!d t'! ti!6"in!.

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    56%S!"$&S 8 ;

    Us! t'! P)6Sn dia&$a )!"#+ t# ans+!$ t'! f#""#+in& 0u!sti#n.

    (Pb) + (Sn)

    L + (Pb)

    L+ (Sn)(Pb)

    (Sn)

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    1. T'! %#nstituti#n (#int f#$ a Sn6 +t> P) a""#* at 25C "i!s

    in a t+#6('as! fi!"d. C#nst$u%t a ti!6"in! #n t'! fi&u$! and$!ad #ff t'! t+# ('as!s and t'!i$ %#(#siti#ns.