Advanced Materials - 230516

Question 1

advantage aluminum

Answer 1

less weight
expensive cars, lots of aluminum

Question 2

al wrought alloys

Answer 2

naturally hard alloys
precipitation hardenable alloys
also Al casting, but not considered in the lecture

Question 3

nomenclature

Answer 3

• EN: Euronorm
• A: Aluminum
• W: wrought (or casting)

or AA (aluminum asociation)

• 4 numbers: 1) which group it belongs to: 1: pure Al, 5: AlMg (not hardenable), 6: AlMgSi (precipitation Hardenable)
• • hardening treatment(s): H1x: strain hardened states, H2x: strain hardened and partially annealed; T: tempering

Question 4

strengthening mechanisms

Answer 4

• Pure aluminum: strain hardening
• Naturally hard alloys (5xxx): strain hardening, solid solution hardening
  *

Question 5

why does strain hardening work?

Answer 5

• dislocation number increases
• temperature below the recystallization T

Question 6

Solid solution hardening

Answer 6

• Mixed crystal.
• the greater the temperature, the more elements can be alloyed with the aluminum. More Mg, more strength
• more Mg, more oschillation or non homogeneus
• more Mg, an abrupt yield point

Question 7

Precipitation hardening procedure

Answer 7

solution annealing
quenching
tempering

Question 8

Precipitation vs. Annealing time

Answer 8

small time: small precipitations, high qty
big time: big precipitations, less qty
dislocation prefer cutting for small time, and bypassing if the time is big enough

Question 9

cutting and bypassing mechanisms

Question 10

overaging

Question 11

artificial and natural aging

Answer 11

natural: embrittlement at room temperature
artificial:

Answer 12

especially adapted to the max strength in the paint baking process