es 67 phase diagrams (2)

8/17/2019 ES 67 Phase Diagrams (2)

1/16

PHASE DIAGRAMS

Illustrates the stable phase/s present ina system at a given condition (pressure,temperature and composition)

Provides a correlation between themicrostructure of materials and itsmechanical properties

Used in the design and control of heattreatment procedures, especially formetals

jdlgamutan2!"


2/16

BASIC TERMS AND CONCEPTS

1. System # speci$c body of material underconsideration

2.Phase # homogeneous portion of a system that

has uniform physical and chemicalcharacteristics

3.Component # pure substances or compounds

of which a system is composed

4.So!"##ty $#m#t # ma%imum concentration ofsolute atoms that may dissolve in the solvent to

form a solid solution jdlgamutan2!"


3/16

System& S%GAR&'ATER S(STEM

Phases& $#)!#* So!t#on Phase an* So#* S!+a, Phas

Components& 'ate, an* S!+a,

Solubility Limit & -a,#es #th T as #n*#/ate* #n the +,ap

stration of the Basic Concepts

jdlgamutan2!"


4/16

One&Component o, %NAR( Phase D#a+,am

'implest and easiest type of phase diagram omposition is held constant, diagram is that of apure substance

Phase Bo!n*a,#es

# at any point on thesecurves, phases on eitherside of the curve coe%istwith one another

T,#pe0Ina,#antPo#nt # all three phasesof a substance (solid,liuid, gas) are

simultaneously ine uilibrium jdlgamutan2!"


5/16

o&Component o, B#na,y Phase D#a+,a

Pressure is held constant, temperatureand composition are variable

*%tremely common and applicable tobinary alloys

pes of Binary Phase Diagrams:

1.B#na,y Isomo,pho!s System

2.B#na,y E!te/t#/ System

jdlgamutan2!"


6/16

o,pho!s System COPPER&NICE$ S(STEM

$#)!#* Phase #+omogeneous liuid solutionof u and i

&Phase # 'ubstitutionalsolid solution of u and i

**Cu and Ni are completely soluble in the solid

state due to the fact that both metals possess thesame FCC cr stal structure

-elting .emperatures&

TC! 5 16789C

TN# 5 14839C

jdlgamutan2!"


7/16

Inte,p,etat#on o: Phase D#a+,ams

PHASES PRESENTLocate the temperaturecomposition point on

the dia!ram and note the phases present" aslabeled.

COMPOSITIONS O; THE PHASES

RE$ATI-E AMO%NTS O; PHASES

PRESENT

jdlgamutan2!"


8/16

PHASES PRESENT

COMPOSITIONS O; THE PHASES(in terms of component concentration)

For sin!le phase re!ions" the composition of this phase

is simply the same as the alloy composition

For t#ophase re!ions"1. Construct a tie line at the !i$en temperature

2. Note the intersection of the tie line and the

phase boundaries 3. From these points of intersection" identify thecomposition of the phase by droppin! a perpendicularline to the compositiona%is

RE$ATI-E AMO%NTS O; PHASES


jdlgamutan2!"


9/16

PHASES PRESENT

COMPOSITIONS O; THE PHASES

RE$ATI-E AMO%NTS O; PHASESPRESENT

For sin!le phase re!ions" alloy is composed entirelyof that phase

For t#ophase re!ions" use the in$erse le$er rule asfollo#s& 1. Construct a tie line at the !i$en temperature 2. 'easure the len!th of the entire le$er" the

!i$en temperaturecomposition point bein! thefulcrum


jdlgamutan2!"


10/16

Illustration

< Po#nt A

Phase/s Present&

&So#* So!t#on

omposition of the Phase&

=6>N#&46>C!

elative 0mount of the Phas

166>

jdlgamutan2!"


11/16

Illustration

< Po#nt B

Phase/s Present&

&So#* So!t#on$#)!#* Phase

omposition of the Phases&

42.8>N#&8?.8>C!

$ 31.8>N#&=7.8>C!

jdlgamutan2!"


12/16

Illustration

< Po#nt B

elative 0mount of the Phas

'$ 5 =7> $

' 5 32>

jdlgamutan2!"


13/16

e/t#/ System COPPER&SI$-ER S(STEM

jdlgamutan2!"


14/16

tant :eat!,es o: a E!te/t#/ B#na,y Phase D#a+,am

h,ee s#n+e&phase ,e+#ons @ an* $#)!#* solid solution of u with 0g as solute solid solution of 0g with u as solute

#m#te* so!"##ty #n the so#* phase

h,ee to&phase ,e+#ons $@ $@

na,#ant o, E!te/t#/ po#nt :oo#n+ the ,ea/t

$ 5

jdlgamutan2!"


15/16

n&I,on Ca,"#*e Phase D#a+,am

jdlgamutan2!"


16/16

G#""s Phase R!e

4ictate the construction of Phase 4iagrams

Proposed by the !5th century physicist 67 8illard9ibbs

epresents a criterion for the number of phasesthat coe%ist within a system at euilibrium

P number of phases present; number of degrees of freedom or e%ternally

controlled variables that can be changedindependently without altering the number of phasesthat coe%ist at euilibrium

C number of components in a system

N number of non:compositional variables (eg7, . jdlgamutan2!"

es 67 phase diagrams (2)

Documents