MSE 220 Fall 2018 - Quiz 4
November 1, 2018
Name: ________Solution__________________________
Discussion 101 102 103 104 105
Honor Pledge (write out):
______________________________________________________________________________
______________________________________________________________________________
Signature: ________________________________
1
, 1. (12 pts) Use the phase diagram on the next page to answer the following:
a. A sample of the alloy Fe 1.0 wt% C is heated to 1200°C and then slowly cooled. After cooling
this alloy to 400°C, answer the following. Clearly label your work and be sure to show and
separately label any compositions you determined and used in your calculations.
What phases are present? What is the fraction of each phase present?
α and Fe3C
Cα = 0.01 wt% C CFe3C = 6.7 wt% C Co = 1 wt% C
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝑜𝑜 6.7 − 1
𝑊𝑊𝛼𝛼 = = = 0.85
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛼𝛼 6.7 − 0.01
𝐶𝐶𝑜𝑜 − 𝐶𝐶𝛼𝛼 1 − 0.01
𝑊𝑊𝐹𝐹𝐹𝐹3𝐶𝐶 = = = 0.15
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛼𝛼 6.7 − 0.01
What microconstituents are present? What is the fraction of each microconstituent present?
Proeutectoid Fe3C and eutectoid α + Fe3C layered structure
Determine amounts of Fe3C and γ at temperature just above eutectoid to determine how much of
each microconstituent is present after the transformation
Cο = 1 wt% C CFe3C = 6.7 wt% C Cγ = 0.76 wt% C
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝑜𝑜 6.7 − 1
𝑊𝑊𝛾𝛾 = = = 0.96
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛾𝛾 6.7 − 0.76
𝐶𝐶𝑜𝑜 − 𝐶𝐶𝛾𝛾 1 − 0.76
𝑊𝑊𝐹𝐹𝐹𝐹3 𝐶𝐶 = = = 0.04
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛾𝛾 6.7 − 0.76
All of the γ becomes the eutectoid α + Fe3C so the fractions of microconstituents are
𝑊𝑊𝑝𝑝𝑝𝑝𝑝𝑝−𝐹𝐹𝐹𝐹3 𝐶𝐶 = 0.04 𝑊𝑊𝛼𝛼+𝐹𝐹𝐹𝐹3 𝐶𝐶 = 0.96
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November 1, 2018
Name: ________Solution__________________________
Discussion 101 102 103 104 105
Honor Pledge (write out):
______________________________________________________________________________
______________________________________________________________________________
Signature: ________________________________
1
, 1. (12 pts) Use the phase diagram on the next page to answer the following:
a. A sample of the alloy Fe 1.0 wt% C is heated to 1200°C and then slowly cooled. After cooling
this alloy to 400°C, answer the following. Clearly label your work and be sure to show and
separately label any compositions you determined and used in your calculations.
What phases are present? What is the fraction of each phase present?
α and Fe3C
Cα = 0.01 wt% C CFe3C = 6.7 wt% C Co = 1 wt% C
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝑜𝑜 6.7 − 1
𝑊𝑊𝛼𝛼 = = = 0.85
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛼𝛼 6.7 − 0.01
𝐶𝐶𝑜𝑜 − 𝐶𝐶𝛼𝛼 1 − 0.01
𝑊𝑊𝐹𝐹𝐹𝐹3𝐶𝐶 = = = 0.15
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛼𝛼 6.7 − 0.01
What microconstituents are present? What is the fraction of each microconstituent present?
Proeutectoid Fe3C and eutectoid α + Fe3C layered structure
Determine amounts of Fe3C and γ at temperature just above eutectoid to determine how much of
each microconstituent is present after the transformation
Cο = 1 wt% C CFe3C = 6.7 wt% C Cγ = 0.76 wt% C
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝑜𝑜 6.7 − 1
𝑊𝑊𝛾𝛾 = = = 0.96
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛾𝛾 6.7 − 0.76
𝐶𝐶𝑜𝑜 − 𝐶𝐶𝛾𝛾 1 − 0.76
𝑊𝑊𝐹𝐹𝐹𝐹3 𝐶𝐶 = = = 0.04
𝐶𝐶𝐹𝐹𝐹𝐹3 𝐶𝐶 − 𝐶𝐶𝛾𝛾 6.7 − 0.76
All of the γ becomes the eutectoid α + Fe3C so the fractions of microconstituents are
𝑊𝑊𝑝𝑝𝑝𝑝𝑝𝑝−𝐹𝐹𝐹𝐹3 𝐶𝐶 = 0.04 𝑊𝑊𝛼𝛼+𝐹𝐹𝐹𝐹3 𝐶𝐶 = 0.96
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