Microstructure of the car.


Dr Adam Wojcik from the Department of Mechanical Engineering examined the microstructure of the car with his microscope, and this is what he saw and said.

The casting method has an effect on the microstructure of the metal.
- In Figure 1 we can see the dentrite shapes (the blobs). The process of moving from liquid to solid metal is what creates these dentrites.
- The dentrites in this car are very close together, which indicates a low porosity in the metal, and therefore high strength.
- Porosity can be seen in Figure 2 (the black spaces in between dentrites). The lack of porosity in Figure 1 shows that this was a high pressure, good quality casting.
- The small dentrites of our specimen (comparing Figure 1 - our car - and Figure 2) show that the metal was cooled quickly.
- The metal is a zinc alloy, evidenced by the fact that we can see the dentrites (white) immersed in another material (the darker colour).

The magnification of the photographs of the car (Figures 1 and 3) is 400x. To give an idea of the scale of these images, consider that the scratch in Figure 3 is the width of a human hair.