1. Lecture 2: Introduction to Aluminum Alloys
MATSE 259
Lecture 2: Introduction to Aluminum Alloys
Christopher L. Muhlstein, Ph.D.
Department of Materials Science and Engineering
The Pennsylvania State University
University Park, PA

2. Last Lecture Fundamentals of materials science and engineering
Classes of materials properties
Three classes of materials
Steel nomenclature

3. Lecture 2: Key Concepts and References
Aluminum alloy nomenclature
Introduction to phases
Reference (Callister)
sects. 3.12, 4.3, 5.1
pps
chapter 6

4. Al Structural Alloys Lotus Elise 190 hp 1984 lbs 0-60 mph - 4.9 sec
top speed mph mpg highway $46K

5. Automotive Application of Al Alloys
Lotus versatile vehicle architecture system (VVA)
Almost all “aluminum high pressure die-castings, stampings, and extrusions
Advanced Materials & Processes, July 2005, p 29

6. Which “aluminum” is it?
Not the same designation system as steels

7. Aluminum Alloy Overview
Low density (~34% of steel)
High thermal and electrical conductivity
Corrosion resistant in ambient air
Low melting point (660°C)
Modified mechanical properties via cold work, alloying, and heat treating

8. Aluminum Alloy Nomenclature
Aluminum Association Number
4 digit number + temper designation (letter and sometimes numbers)
Wrought vs. cast designation
4 digits, no punctuation (e.g. 6061)
4 digits, decimal point between last two digits (e.g )

9. Wrought Aluminum Alloy Nomenclature
First digit indicates alloy group
1XXX Aluminum ≥99.00%
2XXX Copper
3XXX Manganese
4XXX Silicon
5XXX Magnesium
6XXX Magnesium + Silicon
7XXX Zinc
8XXX other elements
9XXX Unused series

10. 1XXX Series Wrought Aluminum Alloys
10XX are unalloyed
Last two digits give minimum aluminum percentage
1035 contains 99.35% aluminum
The second digit indicates control over specific impurities (e.g. silicon)

11. Cast Aluminum Alloy Nomenclature
First digit indicates alloy group
1XX.X Aluminum >99.00%
2XX.X Copper
3XX.X Silicon with added copper and/or magnesium
4XX.X Silicon
5XX.X Magnesium
7XX.X Zinc
8XX.X Tin
9XX.X Other elements
Second two digits identify specific alloy
Last digit indicates casting (0) or ingot (1)
Letter may be appended, in some cases

12. 1XX.X Series Cast Aluminum Alloys
Second two digits indicate minimum aluminum percentage
135.0 Aluminum is a 99.35% aluminum casting
135.1 Aluminum is a 99.35% aluminum ingot

13. Material Structure Amorphous materials Single crystal materials
Polycrystalline materials
Grain boundaries
Isotropic and anisotropic properties
Small crystalline nuclei
Growth of crystallites
Solidified
Optical micrograph
Schematic of stages of solidification of a polycrystalline material; the square grids depict unit cells
Callister, Materials Science and Engineering: An Introduction (2003)

14. Structural Materials are Complicated!
Names?
Crystal structure(s)?
Microstructure?
Transmission electron micrograph of 7150-T651
Optical micrographs of various cast irons.
Callister, Materials Science and Engineering: An Introduction (2003)

15. Microstructural Evaluation (Optical)
Optical Microscopy
Grind
Polish
Etch/stain/anodize
Image

16. Etchants Reveal Microstructure
Polished Gray Iron
Polished and Etched Gray Iron

17. Wrought Aluminum Microstructures
10% Reduction
40% Reduction
5457-O plate, Barker’s reagent
80% Reduction
ASM, Metals Handbook Volume 9 (1995)

18. Steel Microstructures
Pearlite
Tempered Martensite
Martensite
Spheroidite
Callister, Materials Science and Engineering: An Introduction (2003)