3.3 alloys
TRANSCRIPT
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