Chapter 6 Nonferrous Metals and Alloys Nonferrous Metals

Chapter 6 Nonferrous Metals and Alloys

Nonferrous Metals and Alloys • • • Alloys containing no iron Usually more expensive than ferrous metals Have wide range of applications.

Aluminum and Al Alloys • • • Most abundant metallic element in the earth’s crust (8%), second to iron in production. Nonmagnetic, good corrosion resistance. High thermal and electrical conductivity. High strength to weight ratio. Easy to form (containers and packaging, aircraft and aerospace applications, marine craft, electrical components, etc. ). Commercially pure aluminum (99. 5 - 99. 7%).

Magnesium and Mg Alloys • • Third most abundant metallic element in the earth s crust (2%). Come from sea water - obtained electrolytically or by thermal reduction. Lightest engineering metal available. Good vibration dampening characteristics.

Magnesium Alloys (Cont. ) • High strength to weight ratio (alloyed with other elements) • Used for aircraft and missile components, material handling equipment, lightweight components. • Oxidizes rapidly (pyrophoric) precautions should be taken when machining, grinding, etc.

Copper and Cu Alloys • • Best conductor of electricity and heat, good corrosion resistance Non-magnetic Used for electrical components, springs, cooking utensils. Brass and Bronze are the two most common alloys of copper (zinc-Zn and tin-Si).

Superalloys • • • Strong, high corrosion and heat resistance, resistant to fatigue and creep Used in high temperature applications (jet engines, turbines, nuclear industry). Nickel (Ni)-based Alloys • • • most common. magnetic (used for electromagnetic applications). Others include Cobalt (Co)-based alloys, Iron (Fe)-based alloys

Titanium and Ti Alloys • • Expensive High strength to weight ratio, corrosion resistant at high temperatures. Surface contamination from hydrogen, oxygen, or nitrogen cause em-brittlement, reducing toughness, and ductility. Submarine hulls, marine components, jetengine components, orthopedic implants

Refractory Metals and Alloys • High melting point, maintain strengths at elevated temperatures (2000 - 4000 °F). • Molybdenum (Mo) • • • most plentiful of refractory metals. Disadv. Low resistance to oxidation above 950 °F Niobium (Nb) • • also Columbium. Good oxidation resistance

Refractory Metals and Alloys Tungsten (cont’d) • Tungsten (W) • • Highest melting point of any metal– 6170 °F Poor resistance to oxidation Light bulb filaments, spark plugs, welders Tantalum (Ta) • • • High melting point - 5425 °F Good ductility and resistance to corrosion Capacitors, furnaces, heat exchangers

Other Nonferrous Metals and Alloys • Beryllium • • High strength-to-weight ratio Low neutron absorption Toxic. Zirconium • • Good strength and ductility at elevated temperatures Low neutron absorption.

Low-melting Alloys • Lead (Pb) • • High density and ductility. Soft, corrosion resistant. Toxic. Used for piping, cable sheathing, radiation shielding.

Low-melting Alloys (Cont. ) • Zinc (Zn) • • Fourth most utilized metal. Galvanizing. Is an alloy base for casting. Tin (Sn) • Soldering materials, containers, protective coatings.

Precious Metals • Costly, soft, and ductile, used for electrical contacts and terminals, as well as for jewelry, dental, and decorative purposes. • Gold, Silver, Platinum

Shape-memory Alloys • After plastically deformed at room temperature, can return to original shape when heated. • e. g. 55% Ni, 45% Ti. • Thermostats, valves, electrical components

Amorphous Alloys • No long-range crystalline structure (no grain boundaries), atoms randomly packed. • • Also called Metallic Glasses. Contain iron, nickel, and chromium (usually alloyed with carbon, phosphorus, boron, aluminum, and silicon).