HW7-new - [010 ME311 MATERIALS ENGINEERING[110 2011 SPRING HOMEWORK#7 DUE DATE March 25 before class PROBLEM 1 Estimate the number of spherical

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[010] φ [110] θ ME311 MATERIALS ENGINEERING SPRING 2011 HOMEWORK #7 DUE DATE: March 25, before class PROBLEM 1: Estimate the number of spherical clusters in 1mm 3 of copper at its melting point that contain a) 10 atoms and b) 60 atoms. The atomic volume of liquid copper is 1.6x10 -29 m 3 , γ SL is 0.177 J/m 2 , k =1.38x10 –23 J/K and T m is 1356 K. Hint: Consider that at the melting temperature, the free energies per unit volume of the liquid and the solid are the same. PROBLEM 2: Copper (FCC crystal structure) is normally alloyed with additional elements in order to increase its strength. For an alloy with a composition of Cu (80 wt%) and Ag (20 wt%) (check the Cu-Ag phase diagram), when the first solid nucleates from the liquid, spherical clusters of radius r form with interfaces having an interfacial energy of 250 mJ/ m 2 . Assuming that the latent heat of melting, L T is 4.8x10 8 J/m 3 , determine the critical radius for nucleation if the sample is cooled from the single-phase liquid region to a
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This note was uploaded on 09/04/2011 for the course ME 311 taught by Professor Meyers during the Spring '08 term at University of Texas at Austin.

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HW7-new - [010 ME311 MATERIALS ENGINEERING[110 2011 SPRING HOMEWORK#7 DUE DATE March 25 before class PROBLEM 1 Estimate the number of spherical

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