Lec 3 - ENGR ENGR 4250 Advanced Materials Engineering...

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ENGR 4250 ENGR 4250 – Advanced Materials Engineering Lecture3 Introduction Introduction -3
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he Lever Rule • Tie line – connects the phases in equilibrium with each other - essentially an isotherm The Lever Rule How much of each phase? Think of it as a lever 1300 T (°C) L (liquid) tie line M L M α α B T B R S R M S M = 20 1200 (solid) 30 40 50 C C L C α S R L α C C R C C S M wt% Ni o Adapted from Fig. 9.3(b), Callister 7e. L L L L L L C C S R W C C S R M M W = + = = + = + = α α α α α 0 0
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4 Strategies for Strengthening: 2: Solid Solutions
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BINARY-EUTECTIC SYSTEMS
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Microstructures in Eutectic Systems:1&2
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Microstructures C o = C E Result: Eutectic microstructure (lamellar structure) in Eutectic Systems: III --alternating layers (lamellae) of α and β crystals. Micrograph of Pb-Sn utectic T (°C) eutectic microstructure Pb-Sn ystem 300 L L + α L : C o wt% Sn system L + β 200 α β 183°C T E Adapted from Fig. 9.14, Callister 7e. 160 μ m α + β 100 α : 18.3 wt%Sn β : 97.8 wt% Sn Adapted from Fig. 9.13, Callister 7e. C , wt% Sn 20 60 80 100 0 40 18.3 97.8 C E 61.9
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Microstructures 18.3 wt% Sn < C o < 61.9 wt% Sn Result: in Eutectic Systems: IV α crystals and a eutectic microstructure C α = 18.3 wt% Sn • Just above T E : T (°C) L : C o wt% Sn L α C L = 61.9 wt% Sn S R + S W α = = 50 wt% Pb-Sn system 300 L L + α L α S R S R W L = (1- W α ) = 50 wt% • Just below T E : 183wt%Sn L + β 200 α β T E primary α eutectic α eutectic β C α = 18.3 wt% Sn C β = 97.8 wt% Sn S W α = = 73 wt% 0 0 0 00 100 0 α + β 18.3 61.9 97.8 R + S W β = 27 wt% Adapted from Fig. 9.16, Callister 7e. C o , wt% Sn 20 60 80 100 0 40
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Lead-Tin System alpha and eutectic phases
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MICROSTRUCTURES IN EUTECTIC SYSTEMS
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Microstructures α α 75 α α α α A BC 175 μ m L + α 00 300 L α T (°C) β β L + β α + β 200 100 β T E β β β β C o , wt% Sn 20 60 80 100 0 40
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ypo utectic & yper utectic L + α 300 L Hypo eutectic & Hyper eutectic Adapted from Fig. 9.8, allister 7e ig 9 8 T (°C) L + β α + β 200 100 α β T E (Pb-Sn System) Callister 7e. (Fig. 9.8 adapted from Binary Phase Diagrams , 2nd ed., Vol. 3, T.B. Massalski (Editor-in- Chief), ASM International, Materials Park, OH, 1990.) C o , wt% Sn 20 60 80 100 0 40 hypereutectic: (illustration only) hypoeutectic: C o = 50 wt% Sn 61.9 eutectic β β (Figs. 9.14 and 9.17 from Metals Handbook , 9th ed., Vol. 9, Metallography and α α eutectic: C o =61.9wt% Sn 160 m β β β β Microstructures , American Society for Metals, Materials Park, OH, 1985.) 175 μ m α α α α μ eutectic micro-constituent Adapted from Fig. 9.14, Callister 7e. Adapted from Fig. 9.17, Callister 7e. (Illustration only) Adapted from Fig. 9.17, Callister 7e.
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on- arbon (Fe- ) Phase Diagram Iron Carbon (Fe C) Phase Diagram 1600 δ T (°C) 1400 1200 1000 1148°C 800 α 600 400 0 123456 6 . 7 (Fe) C o , wt% C
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on- arbon (Fe- ) Phase Diagram Iron Carbon (Fe C) Phase Diagram 1600 δ T (°C) 1400 L γ γ + L ) 1200 1000 (austenite) L +Fe 3 C 1148°C cementite 800 γ +Fe 3 C α Fe 3 C ( c 600 α +Fe 3 C 400 0 123456 6 . 7 (Fe) C o , wt% C
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on- arbon (Fe- ) Phase Diagram Iron Carbon (Fe C) Phase Diagram • 2 important points 1600 δ T (°C) - utectoid ( -Eutectic ( A ): L ⇒γ +Fe 3 C e) 1400 1200 L γ ustenite) γ + L L +Fe 3 C 1148°C A Eutectoid ( B ): γ⇒α 3 C cementit e 1000 00 (austenite) γ +Fe 3 C 27° =T utectoid S R γ γ γ γ Fe 3 C ( c 800 600 α +Fe 3 C α 727 C = T eutectoid R S B 400 0 123456 6 . 7 (Fe) C o , wt% C 4.30 Result: Pearlite = lternating la ers of
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This note was uploaded on 10/18/2010 for the course ENGR 3360 taught by Professor Ahmadbarari during the Fall '10 term at UOIT.

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Lec 3 - ENGR ENGR 4250 Advanced Materials Engineering...

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