Engineering Materials - Manufacturing Engineering and Technology

8/17/2019 Engineering Materials - Manufacturing Engineering and Technology

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Engineering Materials





How to Read a PhaseDiagram

• Rule 1: If we know T and Co, then we know: --the # and types of phases present.

• Exaples:

Cu-Niphase

diagram

!:1 phase "α

$:

% phases "& ' α




• Rule %: If we know T and Co, then we know: --the (opos)t)on of ea(h phase.

Exaples:

Cu-Nisystem

• C0 = 35 wt% Ni

• At 1300 C – !"#y #i$uid &'

– C& = C0 = 35 wt% Ni'

• At 1150 C

– !"#y so#id α'

– Cα = C0 = 35 wt% Ni'

• At ()

– )oth α a"d &

– C& = C#i$uidus = 3* wt%

Ni'

– C α = Cso#idus =+3 wt%




• Rule *: If we know T and Co, then we know: --the aount of ea(h phase "+)en )n wt. Cu-Ni

system• C / *0 wt )

• !t 1* C:

– 2nly l)3u)d "&

– 4& / 1 wt, 4α / wt

• !t 110 C:

– 2nly sol)d "α

– 4& / wt, 4α / 1 wt

• !t T$: – $oth α and &

– 4& / 56"R'5 /

"7*-*06"7*-*% / 8* wt

– 4α / R6"R'5 /

"*0-*%6"7*-*% / %8 wt

(he #e,er ru#e



(he &e,er Ru#e A Proo

. /um o weight ratio"s

. Co"ser,atio" o mass Ni'

. Comi"e ao,e e$uatio"s

. A geometri i"terpretatio"



E!" Mg$%i &ystem

'uestion" (elow is given the phase diagram of the binary system Mg$%i. )hat are the compositions of the phases in e*uilibrium when the overall composition of the solid is +- Mg and/- %i0 at 123 #. &ame *uestion for 1- Mg, and 4- Mg

.

Answer"

#omposition in +- Mg,

li*uid with 15- Mg 6 solid with +7- Mg8

in 1 - Mg, single phase li*uid solution8

9n 4 - Mg, single phase solid solution.



A B

CD

E F

G

HJ

N

K PP S

Q

L

α

δ

γ

Fe3C

L+δ

δ +γ

γ+α

L+γL+Fe

3C

γ+Fe3C

α+Fe3C

L+δ+γ L+γ+Fe3C

γ +α+Fe3C



How to :ead ;e$# Phase Diagram

(he diagram shows three hori2o"ta# #i"es whih i"diate isotherma# reatio"s o"oo#i"g heati"g'

• 4irst hori2o"ta# #i"e is at 1+06C7 whereperiteti reatio" ta8es p#ae&i$uid 9 δ : auste"ite

• /eo"d hori2o"ta# #i"e is at 11306C7 where

euteti reatio" ta8es p#ae#i$uid : auste"ite 9 eme"tite

• (hird hori2o"ta# #i"e is at ;*36C7 whereeutetoid reatio" ta8es p#ae

auste"ite : pear#ite mi<ture o



E!" ;e$# &ystem

'uestion")hat phases are present, what are their compositions and what are their compositions and what are their relative amounts for each of thefollowing points on the ;e$# phase diagram?

a'<-#, < 3 #' <-#,=1+ 3 #

' <- #, =11 3 #

d' ./-#, =1+ 3 #

e' ./-#, =11 3 #



E!" ;e$# &ystem



E!" Pb$&n &ystem

'uestion"a' )hat is the eutectic temperature? )hat is the eutectic compositio

n?

' &uppose an alloy contains 15- tin overall, what are the compositions of the phase in e*uilibrium at the eutectic temperature 6.5 3#, and >.5 3 #?

' A Pb$&n alloy contains +5- &n.

i> )hich phases are in e*uilibrium at < 3 #?

ii> Apply the lever rule to find the relative amounts of each phas

e.

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Engineering Materials - Manufacturing Engineering and Technology