Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MAT SCI 298 > Lecture 6 - Aluminum Alloys > Flashcards

Lecture 6 - Aluminum Alloys Flashcards

1
Q

What is the crystal structure of pure Al?

A

FCC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the melting point of pure Al?

A

660.2C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the boiling point of pure Al?

A

2480C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the mean specific heat for pure Al?

A

.219 cal/gC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the thermal conductivity for pure Al?

A

.57cal/cms*C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the co-efficient of linear expansion for pure Al?

A

23.5 x10^-6/C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the electrical resistivity for pure Al?

A

2.69 ohm*cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the modulus of elasticity for pure Al?

A

68.3 GPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the Poissons Ratio for pure Al?

A

0.34

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Al is _______ than Cu. Coarse-grained Al is one of the __________materials in the world.

A

softer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Al has the ______________________________ among all FCC metals

A

highest stacking fault energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the two major categories of Al alloys?

A

cast and wrought

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are five properties of cast AL alloys?

A

high alloy content 8-12 wt %
cast-to-shape
little heat treatment
low mechanical properties (120-300 MPa UTS, strain 5%)
cheap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are five properties of wrought Al alloys?

A

low alloy content 1-3%
made into standardized products (sheets, rods, bars, tubes)
extensive heat treatment, solutionizing, aging
550 MPa UTS, strain 5-20%
wide-range of applications

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are five common issues to printing aluminum alloys in L-PBF (wrought)?

A

low laser absorptivity (minor due to low melting temp)
Al is prone to oxidation
high residual stress
hot cracking (solidification cracking, hot-tearing)
composition control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does hot cracking occur?

A

contraction of solid phase and liquid phase in large semi-solid zone specific to wrought Al alloys produces poor fluidity

17
Q

Why are cast Al alloys not susceptible to hot cracking?

A

low solidification shrinkage, high fluidity, easy to print

18
Q

Why are wrought Al alloys susceptible to hot cracking?

A

large solidification shrinkage, large semi-solid zone, difficult to print

19
Q

How does Si affect Al?

A

Si helps form cellular structures but produces poor elongation

20
Q

How can hot cracking be mitigated?

A

decorate with nanoparticles, but change solidification behavior

21
Q

What do current Al alloy print studies focus on?

A

printability

22
Q

What do nanoparticles do to Al alloys?

A

enhance printability and mechanical properties (not sure about corrosion resistance)

23
Q

Why is 3D printing not the best approach for Al?

A

not high value products (cheap)

24
Q

What does high stacking energy mean?

A

no twinning

25
Q

Which Al series is interested in 3D printing?

A

7000 series

26
Q

Which Al alloy is popular for L-PBF?

A

Al-Si-Mg

27
Q

Why is composition difficult to control?

A

Evaporation of other materials (Zn, Mg)

MAT SCI 298 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions