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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
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