The study of metals
3 Groups of Metallurgy
The study of the extraction and purification of metals from their ores through several steps that increasingly purify the metal by removing unwanted metals
What are 3 routes that Extractive Metallurgy may be carried out?
Melting the ore in a furnace to release the metal
Dissolving the metal from the ore and recovering it as a powder
Dissolving the metal from the ore with the use of electricity
The study of the techniques and mechanical forces that shape and make the finished forms of metal, including the effects of stress, time, and temperature
The study of the structure of metals
What are the properties of metals initmately related to?
How can the properties of a metal be manipulated?
Modification of the structure, e.g. modifying chemical composition, alloys, and heat treatment
1. Good conductors of heat and electricity
2. Generally malleable and ductile
3. Occur naturally in ores in the form of chemical compounds, e.g. sulphides and oxides
4. Tend to corrode, i.e. tend to react chemically with the environment and revert to compound forms, with the exception of noble metals
Are the majority of power plant components iron-based?
What occurs on the atomic level when a solid metal is heated?
1. The atoms of the material increasingly vibrate as the temperature increases
2. At a certain temperature, the substance melts and the cohesive bonds holding the individual atoms together breaks, allowing them to travel freely throughout the liquid
3. At the melting point, heat energy is absorbed without further increase in temperature until all the metal is in liquid state
Does every metal and alloy have a fixed melting point?
Fixed configuration of individual metallic atoms
What are the 3 basic structures of Unit Cells?
1. Face-Centered Cubic (FCC)
2. Body-Centered Cubic (BCC)
3. Close Packed Hexagonal (CPH)
How many atoms make up the Face-Centered Cubic structure?
What are the properties of Face-Centered Cubic?
1. High Ductility
2. Low Shear Strength
3. Low Tensile Strength
4. Good Thermal and Electrical Conductivity
What are some metals that have the FCC structure in solid state?
6. Gamma Iron (910-1390ºC)
How many atoms make up the BCC structure?
What are the properties of BCC?
1. High Strength
2. Low Ductility
3. Very Resistant to Shear Deformities
What are some metals that have the BCC structure in solid state?
5. Alpha Iron (below 910ºC)
6. Delta Iron (above 1390ºC)
How many atoms make up the CPH structure?
What are the properties of CPH?
1. Intermediate Strength
2. Intermediate Ductility
What are some metals that have the CPH structure in solid state?
What happens to unit cells as molten metal cools and solidifies?
They become packed together to form 3D crystals that occupy a space lattice
What happens as unit cells continue to pack together as crystals?
Further growth of these crystals forms dendrites, which look like the branches of an evergreen tree, that extend through the molten matric until they contact neighbouring dendrites. These contact surfaces become the crystal or grain boundaries.
What happens to insoluble solids present in solidifying molten metal?
They are pushed ahead of the growing crystals and become trapped at the grain boundaries and between the limbs of the dendrites.
What effect does grain size have on the properties of metals?
1. Smaller grain size increases tensile strength and ductility
2. Larger grain size tends to resist creep and deformation under constant loading but may be prone to cracking