Hierarchy of Iron Alloys

Numbering System

Low Carbon Steel

Medium Carbon Steel and its Alloys

With a small amount of Si, Fe3C → -Fe and graphite

Cast Iron

Clockwise from upper left: gray cast iron, nodular (ductile) cast iron, white iron and malleable iron

Stainless Steels

Tool Steels

Aluminum Alloys

Copper Alloys

Titanium Alloys

Magnesium Alloys

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• Properties: --Tmelt for glass is moderate, but large for other ceramics. --Small toughness, ductility; large moduli & creep resist.• Applications: --High T, wear resistant, novel uses from charge neutrality.• Fabrication --some glasses can be easily formed --other ceramics can not be formed or cast.

Glasses Clay products

Refractories Abrasives Cements Advanced ceramics

-optical -composite reinforce -containers/ -household

-whiteware -bricks

-bricks for high T (furnaces)

-sandpaper -cutting -polishing

-composites -structural

engine -rotors -valves -bearings

-sensors

TAXONOMY OF CERAMICS

• Need a material to use in high temperature furnaces.• Consider Silica (SiO2) - Alumina (Al2O3) system.• Phase diagram shows: mullite, alumina, and crystobalite (made up of SiO2) tetrahedra as candidate refractories.

6Composition (wt% alumina)

T(°C)

1400

1600

1800

2000

2200

20 40 60 80 1000

alumina +

mullite

mullite + L

mulliteLiquid (L)

mullite + crystobalite

crystobalite + L

alumina + L

3Al2O3-2SiO2

APPLICATION: REFRACTORIES

tensile forceAo

Addie

die

• Die blanks: --Need wear resistant properties!

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• Die surface: --4 m polycrystalline diamond particles that are sintered on to a cemented tungsten carbide substrate. --polycrystalline diamond helps control fracture and gives uniform hardness in all directions.

APPLICATION: DIE BLANKS

• Steels: increase TS, hardness (and cost) by adding-C (low alloy steels)-Cr, V, Ni, Mo, W (high alloy steels)-Ductility usually decreases w/ additions

• Nonferrous:-Cu, Al, Ti, Mg Refractory, and noble metals

• Basic categories of ceramics:-Glasses-Clay products-Refactories-Cements-Advanced ceramics

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SUMMARY