Lecture 8 - Copper Alloys Flashcards
Which elements have higher conductivity than copper?
Silver
What reduces the electrical conductivity?
defects
alloys
What 5 things do defects include?
vacancies
impurities
dislocations
grain boundaries
twins
What are the four unique qualities of pure copper?
high electrical conductivity
high thermal conductivity
excellent ductility and toughness
good corrosion resistance
What happens when copper oxidizes?
degrades conductivity (P and B are added to deoxidize)
What happens when Al is added to Cu?
high strength fine dispersion of Al2O3
What are the four biggest reasons to use copper?
electrical conductivity
corrosion resistance
heat transfer
structural capability
What is brass?
5-40% Zn
What is Nickel Silver?
25% Zn + 10-20% Ni
What is Bronze?
4-12% Sn
What is Phosphor Bronze?
normal bronze + 0.2% P
What is Aluminum Bronze?
normal bronze + 3-10% Al, Fe, Ni, Sn
What is copper-nickel?
10-70% nickel
What is copper beryllium?
1-2.5% Be
Where does the strength of most Cu alloys come from?
solid-solution strengthening
cold working
Which alloys can be precipitation hardened?
Cu-Be and Cu40Zn
What are the five families of coppers?
copper alloys, brass (Zn)
phosphor bronze (Sn)
aluminum bronze (Al)
silicon bronze (Si)
cupronickel, nickel silvers (Ni)
Why is it difficult to use L-PBF on fully dense Cu materials?
low absorptivity against 1070 nm laser
How does the tensile ductility of AM-Cu compare to that of cold rolled Cu with similar yield strength?
Better
What is the biggest application for copper?
electrically conductive materials
Which copper alloy is the most important?
C63000 (NAB)
What are the two most popular techniques for manufacturing C63000?
WAAM and L-DED
What other treatment can precipitation hardened alloys do?
aging treatment
What are two common errors when using L-PBF on Cu?
lack of fusion and overfusion
What is the staircase effect?
pool width makes curved surfaces into steps rather than smooth lines
How is the oxygen impurity level in copper?
relatively low
What are the two processes most used on copper?
L-PBF, EBM
What is the top choice for manufacturing nickel aluminum bronze?
WAAM
What is nickel aluminum bronze used for?
large structures
Why is L-PBF for NAB worse than WAAM?
phase changes result in low ductility
