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Alloys and Their PhasDiagrams

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 The Lever Rule

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Solid Phases

•

Alpha (α) –ferrite• Max Soluility around !"#$%

• &amma (γ) –austenite• Max Soluility around #!'$%

• Delta (δ) –ferrite• Max Soluility around !"$%

• *e+% –%ementite or %aride

• *orms eyond ,!-$%

• Li.uid (L)

• Pearlite –not a phase//•

A lamellar et0een 1ute2toid α and 1ute2toid *e+%

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3inary 1ute2ti2 Alloy System

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4ypoeute2toid vs 4ypereute2to

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1xample Prolem –1valuate at Poin%• 5hat phases are

present6• Alpha and Li.uid

• 5hat are the2ompositions6

•

5Alpha 7 '8!#0t$Sn• 5Li.uid7 ,'!80t$Sn

• 5hat are the amounts of thephases6

• (use the lever rule)

• 9alpha7 (,'!":"!");(,'!8:'8!#) 7

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Sample Prolem

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Solution

•

a! 5t$ Proeute2toid %ementite 7 ('!'" – !");(,<!'$

• ! 5t$ 1ute2toid *errite 7 (,!,- – '!');(,!,- – !"+!$

5t$ 1ute2tiod %ementite = 5t$ 1ute2toid = 5t$Proeute2toid %ementite 7'""$

5t$ 1ute2toid %ementite 7 '""$ : (+!$ = <!'

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A hypoeute2toid steel 2ontains ##!<$ euteferrite! 5hat is the average 2aron 2ontent

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Solution

•

 Total *errite 7 1ute2toid *errite = Proeute2toid *• (,!,- – x);(,!,-:!"#) 7 !##< = (!" – x);(! : !"#)

• x 7 !#

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?uestions6