When casting of A356 alloy in the semi-solid metal processing is carried out then A356 alloy comprises the globular morphology of primary alpha Al. While the A356 alloy cast by the conventional casting method comprises the dendritic morphology. This morphology helps in improving the castability and mechanical properties of A356 alloy. The solidification range in the SSM cast A356 alloy should be higher or lower than the solidification range of conventional cast A356 alloy.
1. issue: The solidification range is just a matter of thermodynamics. The phase diagram, i.e. the different between liquidus and solidus for a given alloy concentration determines the solidification range. The solidification range does not depend on the kinetics of solidification. However,
2. issue: the nucleation of the primary phase requires some supercooling below the liquidus line. This is for most casting processes (I exclude rapid solidification processes) in the range of less than 1 K. The nucleation supercooling can be measured in a DTA experiment. Therefore the solidification range of an alloy is given by its concentration or the state point in the phase diagram.
3. issue: Look into standard textbooks on solidification (Kurz-Fisher, Stefanescu, Fredriksson, Glicksman...)
Thank you sir for your kind reply this will help me in my research work.
Dear Robin Gupta,
I think that the discussion of the present issue should also take into account possible results of the discussion about your question 'How the formation of eutectic Si takes place in the Rheometal process ?' as both questions address aspects of the solidification of the A356 alloy. Perhaps, answers to one of the questions may help to find answers to the other question. Good luck!
As L.Ratke told you the solidification range is the same for all A356 alloys because it's due to it composition. However if you change the cooling/heating rate and/or the "nucleation potential" you will measure different transformation temperature due to the fact that you may not be in thermodynamic equilibrium (The solidification range is generally given for equilibrium, you can compare Fe-C and Fe-Fe3C diagram as an example).
The morphology of your structure is closely linked to the neighbourhood of the solidified phase and its interaction with it (superficial tension at liquid/solid interface). There is an example for the as-cast AS13 aluminium alloy where the euttecic phase morphology can be modified thanks to small additions of Na or Sr this kind of treatment also exist for other kind of alloys (ex: gray and SG iron)...
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Inorganic Materials
- Metals
- Alloys