3.3 alloys

3.3 ALLOYS AND NON-FERROUS METALS

• 3.3.1 Alloys

• 3.3.2 General properties

• 3.3.3 The common metals and alloys

• 3.3.4 Electroplating

Schematic of atoms in two different metals

When metal are mixed to form alloys there are 3 possibilities:

• Completely soluble, i.e. atoms of one will fit exactly into the structure of the other without disturbing it. (e.g. copper and nickel)

• Partially soluble, i.e. the atoms cannot form structures together but crystals of each will mix. (e.g. copper and zinc i.e. brass)

• Insoluble, e.g. molten iron will float on molten lead, they will not mix

Completely Soluble

When metal are mixed to form alloys there are 3 possibilities:

• Completely soluble, i.e. atoms of one will fit exactly into the structure of the other without disturbing it. (e.g. copper and nickel)

• Partially soluble, i.e. the atoms cannot form structures together but crystals of each will mix. (e.g. copper and zinc i.e. brass)

• Insoluble, e.g. molten iron will float on molten lead, they will not mix

Partially soluble

When metal are mixed to form alloys there are 3 possibilities:

• Completely soluble, i.e. atoms of one will fit exactly into the structure of the other without disturbing it. (e.g. copper and nickel)

• Partially soluble, i.e. the atoms cannot form structures together but crystals of each will mix. (e.g. copper and zinc i.e. brass)

• Insoluble, e.g. molten iron will float on molten lead, they will not mix

Insoluble

3.3 ALLOYS AND NON-FERROUS METALS

• 3.3.1 Alloys

• 3.3.2 General properties

• 3.3.3 The common metals and alloys

• 3.3.4 Electroplating

Thermal Properties

Densitykg/m3

Specific HeatJ/kg/oC

Thermal conductivityW/moC

Coefficient of thermal expansion/oC10-6

Copper 8900 390 300 17

Steel 7800 480 84 11

Aluminium 2700 880 200 24

Mechanical Properties

Effect of cold working of typical metal

Percentage elongation

Tensile Strength

Percentage change in cross section areaduring cold working

3.3 ALLOYS AND NON-FERROUS METALS

• 3.3.1 Alloys

• 3.3.2 General properties

• 3.3.3 The common metals and alloys

• 3.3.4 Electroplating

Copper-zinc-tin alloys

Range of non-ferrous alloys

Some of the main non-ferrous alloys used in construction

• Copper

• Zinc

• Aluminium

• Lead

The 3 grades of copper are • Deoxidised copper, used for copper tube, suitable

for welding.• Fire refined tough pitch copper, had higher

strength, thermal and electrical conductivity and resistance to corrosion. Used for roof coverings. These turn a pleasant green as surface corrosion occurs. This corrosion product may stain adjacent materials.

• Electrolytic tough pitch high conductivity copper. Contains fewer impurities, has higher electrical conductivity, used for electrical conductors.

Lead and Copper Roofing

Some of the main non-ferrous alloys used in construction

• Copper

• Zinc

• Aluminium

• Lead

Galvanised (zinc plated) steel in fence and structure

Some of the main non-ferrous alloys used in construction

• Copper

• Zinc

• Aluminium

• Lead

Lead roof (note welded repair)

Note staining on bricks from lead roof

3.3 ALLOYS AND NON-FERROUS METALS

• 3.3.1 Alloys

• 3.3.2 General properties

• 3.3.3 The common metals and alloys

• 3.3.4 Electroplating

Electroplating