ENGR302Wk6-1

ENGR302Wk6-1 - L phase region at 1340°C = ~57 wt Ni c At what T does complete melting of the alloy occur The alloy passes into L phase completely

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California National University ENGR 302 Kathryn Toth Week #6 Assignment #1 3/15/2011 Chapter 9 Concept Checks:
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9.1) The difference between a phase equilibrium and a metastability is that in a phase equilibrium the two components are in the completely stable. This means that over time, with the same conditions, nothing will change. The free energy is at a minimum. However, with metastability, the system is approaching stability and has not actually achieved it yet. The changes might be slight, but over time, the system will still undergo changes. 9.2) A 70%Wt Ni-30%Wt Cu alloy is heated slowly from 1300 ° C a) At what T does the first L phase form? ~1340 ° C b) What is the C o of this L form? So we take the intersection of the (α + L )- L phase boundary, then draw a tie line across the α +
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Unformatted text preview: L phase region at 1340°C = ~57 wt% Ni c) At what T does complete melting of the alloy occur? The alloy passes into L phase completely at ~1370 ° C d) What is the C o of the last ∝ prior to complete melting? We take the intersection of the 1370 ° C and the Liquidus line, then draw a tie line over across the ∝+ . L phase We are able to deduce the C o that the last solid had by drawing a line straight to the composition axis. ~78%Wt Ni 9.7) For a ternary system, temp is a variable, pressure is constant, what is the max # of phases? Using the equation for Gibbs phase rule, where components are 3 and pressure is constant (N=1). P + F = C + N = 3+1 = 4 P = 4-F. To find the max # of phases, we let the degrees of freedom = 0, so P=4....
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This note was uploaded on 03/18/2011 for the course ENGR 302 taught by Professor Clausson during the Spring '11 term at CNUAS.

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ENGR302Wk6-1 - L phase region at 1340°C = ~57 wt Ni c At what T does complete melting of the alloy occur The alloy passes into L phase completely

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