Phase Diagram of Al-Si system

The picture above, shows the phase diagram of Al-Si system. Looks phase are there for all Al-Si alloys in the temperature range of 300C-1500C, the image to the left, and in the range of 400C-1400C image to the right for a variety of compositions.

In the phase diagram above, α (fcc crystal structure) and β (bcc crystal structure) is used to indicate two distinct phases each used to indicate the phase of Al and Si. From the phase diagram above we can analyze that an alloy compound consisting of approximately 98% Al and 2% Si is heated slowly from room temperature to 1500C. Then phase that occurs during the heating process takes place is:

            Room temperature to 550C α + β

            550˚C up to 600˚C α

            600˚C up to 660˚C α + liquid

            660 ˚C to 1500C liquid

• single crystals are formed only in the liquid phase. So from the above analysis, it can be concluded that the single crystal is formed by combining Al and Si respectively by 98% and 2%, then heated at a temperature range between about room temperature up to 700˚C, to form a liquid phase. After that, to separate components of a single crystal (most likely, obtained single crystal Al ratio 98: 2) to do the synthesis process.

• a polycrystalline material that has a lot of crystal grain boundaries (grain boundary) accompanying and has a random orientation. From the analysis of the phase diagram above, it can be seen that in order to form a polycrystalline from a mixture of Al and Si, can be obtained through the alloy composition of Al and Si respectively 98% and 2% with the sintering temperature in the range of approximately heating from room temperature to a temperature of 550 ˚C. So that in these conditions will be obtained will be two phases simultaneously, namely α and β phase.

• oriented polycrystalline is polycrystalline which has a spin (domain) direction. It can be obtained, by providing a magnetic field in the polycrystalline material. Until eventually be obtained polycrystalline yanng own spin (domain unidirectional). The direction of spin in the polycrystalline material can be seen through AFM (Atomic Force Microscope) .Polikristal oriented, can be found in the phase (α + L) or (β + L), so if we combine the components Al: Si 98%: 2%, it can be we sintering of a temperature range between room temperature up to about the temperature of 660˚C.

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