- Metals Pure posses generally
● thermal conductivity and excellent electrical (eg. Cu and Al)
● ductility higher, higher melting point, lower yield point and tensile strength
● corrosion resistance improved compared with alloys
- Metals Pure melt and only solidify at temperatures that may be termed as Melting Point or Freezing Point, is in a solid state.
- Above freezing point of the liquid metal and below freezing point, it is in a solid state.
- If the number of temperature measurements taken at different times, although pure metals cooled under equilibrium conditions from the molten state till it solidifies, will receive up TimeTemperature.
1. Liquid metal from A to B.
2. From B to C, liberates the latent heat of fusion melting; A constant temperature.
3. The liquid metal starts solidifying at B and is partly solid at any point between B and C and C is the only solid metal.
4. From C to D, the solid metal cools and tends to reach room temperature.
5. Feels slopes AB and CD of the separate rounds of liquid and solid metals respectively.
If pure metal cools quickly or even otherwise when he is very pure and doesnot at all impurities as crystallization nuclei to start.
1. not nucleation of solid starting point B (ie normal solidification temperature) but it does so at C ie after the supercooled liquid metal. The phenomenon known as supercooling or undercooling.
2. In addition to pure metal, supercooling may occur in alloys, eg. Gray cast iron.
● Undercooling-temperature must cool the liquid metal below the equilibrium freezing temperature before nucleation occurs.
● Recalescence-the increase in temperature of liquid metal undercooled lead to the liberation of heat during nucleation.
● Catch-A plateau of the curve Thermal cooling during the solidification of material caused by the evolution of the latent heat of fusion during solidification.
● The full-time solidification time required for the casting to solidify completely after casting has been poured.
● time-the Local solidification time required for a particular location in early solidify solutions and nucleation started.
- The approval of pure metal (and some eutectic alloy) to solidify in the mold begins the part of the molten metal near the mold wall to solidify.
- The metal solidifies in the form of solid skin and then the liquid metal tends to freeze it.
- Progress of the strong skin toward the center of the mold from the mold walls.
- As the successive layers of molten metal build up in the form of solid skin or increasing the wall thickness of solid metal, the liquid level drops in the model due to solidification shrinkage.