Lecture 8 - Copper Alloys Flashcards

1
Q

Which elements have higher conductivity than copper?

A

Silver

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2
Q

What reduces the electrical conductivity?

A

defects
alloys

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3
Q

What 5 things do defects include?

A

vacancies
impurities
dislocations
grain boundaries
twins

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4
Q

What are the four unique qualities of pure copper?

A

high electrical conductivity
high thermal conductivity
excellent ductility and toughness
good corrosion resistance

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5
Q

What happens when copper oxidizes?

A

degrades conductivity (P and B are added to deoxidize)

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6
Q

What happens when Al is added to Cu?

A

high strength fine dispersion of Al2O3

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7
Q

What are the four biggest reasons to use copper?

A

electrical conductivity
corrosion resistance
heat transfer
structural capability

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8
Q

What is brass?

A

5-40% Zn

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9
Q

What is Nickel Silver?

A

25% Zn + 10-20% Ni

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10
Q

What is Bronze?

A

4-12% Sn

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11
Q

What is Phosphor Bronze?

A

normal bronze + 0.2% P

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12
Q

What is Aluminum Bronze?

A

normal bronze + 3-10% Al, Fe, Ni, Sn

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13
Q

What is copper-nickel?

A

10-70% nickel

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14
Q

What is copper beryllium?

A

1-2.5% Be

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15
Q

Where does the strength of most Cu alloys come from?

A

solid-solution strengthening
cold working

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16
Q

Which alloys can be precipitation hardened?

A

Cu-Be and Cu40Zn

17
Q

What are the five families of coppers?

A

copper alloys, brass (Zn)
phosphor bronze (Sn)
aluminum bronze (Al)
silicon bronze (Si)
cupronickel, nickel silvers (Ni)

18
Q

Why is it difficult to use L-PBF on fully dense Cu materials?

A

low absorptivity against 1070 nm laser

19
Q

How does the tensile ductility of AM-Cu compare to that of cold rolled Cu with similar yield strength?

20
Q

What is the biggest application for copper?

A

electrically conductive materials

21
Q

Which copper alloy is the most important?

A

C63000 (NAB)

22
Q

What are the two most popular techniques for manufacturing C63000?

A

WAAM and L-DED

23
Q

What other treatment can precipitation hardened alloys do?

A

aging treatment

24
Q

What are two common errors when using L-PBF on Cu?

A

lack of fusion and overfusion

25
What is the staircase effect?
pool width makes curved surfaces into steps rather than smooth lines
26
How is the oxygen impurity level in copper?
relatively low
27
What are the two processes most used on copper?
L-PBF, EBM
28
What is the top choice for manufacturing nickel aluminum bronze?
WAAM
29
What is nickel aluminum bronze used for?
large structures
30
Why is L-PBF for NAB worse than WAAM?
phase changes result in low ductility