BARC-2: Solid Aluminium has FCC Structure. It is melted to liquid (which is no crystal structure) and again cooled down slowly. How does Aluminium know that it has to solidify again as FCC? Why does it not solidify as BCC ?
BARC-2: Solid Aluminium has FCC Structure. It is melted to liquid (which is no crystal structure) and again cooled down slowly. How does Aluminium know that it has to solidify again as FCC? Why does it not solidify as BCC ?
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While solidifying from liquid state metal forms small clusters and these clusters can be in different crystal structure. But the crystal structure which have least lattice energy for that cluster of metal is stable and grow more while others dissociate back. In case of Al, FCC has less lattice energRead more
While solidifying from liquid state metal forms small clusters and these clusters can be in different crystal structure. But the crystal structure which have least lattice energy for that cluster of metal is stable and grow more while others dissociate back.
In case of Al, FCC has less lattice energy than BCC, thus it is more stable.
See lessEven though Liquid has no structure it has short-range order. That is over a few lattice distances, crystal structures exist. Now coming to the Question of why FCC? If you take the same metal in different crystal structures like FCC, BCC, HCP... The structure which has the lowest Free Energy will beRead more
Even though Liquid has no structure it has short-range order. That is over a few lattice distances, crystal structures exist.
Now coming to the Question of why FCC? If you take the same metal in different crystal structures like FCC, BCC, HCP… The structure which has the lowest Free Energy will be stable.
For Aluminium it turns out that the FCC structure is stable up to the melting point. Hence it solidifies as FCC
For Metals like Fe & Ti…Allotropism is possible at different temperature ranges, and hence different structures are stable.
I will continue my 3rd Question from here.
See lessI agree for liquids we have short range order small clusters of original structure and it grows during solidification. Suppose when we cool from gaseous state the crystal structure remain same or different ? Justify your answer.
I agree for liquids we have short range order small clusters of original structure and it grows during solidification.
Suppose when we cool from gaseous state the crystal structure remain same or different ? Justify your answer.
See lessIn that case atoms don't have sufficient time to check for possible crystal stucture and redistribute itself into fcc crystal structure. Hence we ends up in amorphous glass structure region. But remember when i say fast it means it has to be super super fast to avoid any possible chance of crystal nRead more
In that case atoms don’t have sufficient time to check for possible crystal stucture and redistribute itself into fcc crystal structure. Hence we ends up in amorphous glass structure region. But remember when i say fast it means it has to be super super fast to avoid any possible chance of crystal nucleation.
See lessAPF is important, the atomic packing factor, that is the reason FCC has more slip systems, because of the way the atoms are arranged in the crystal. Thus FCC metals deform easier than BCC metals and thus they are more ductile. BCC metals are infact stronger than FCC metals. While solidifying from liRead more
APF is important, the atomic packing factor, that is the reason FCC has more slip systems, because of the way the atoms are arranged in the crystal. Thus FCC metals deform easier than BCC metals and thus they are more ductile. BCC metals are infact stronger than FCC metals.
While solidifying from liquid state metal forms clusters which can be in different crystal structure. But the crystal structure which have Lower lattice energy for that cluster of metal is stable and grow more while others dissociate back.
Al, FCC has less lattice energy than BCC, which is more stable.
See lessThe using simulation (first principle calculation) it possible to find the free energy of aluminum in bcc, fcc, hcp phase. Once you get the output you will see that the fcc structure has lowing energy compared to other possible structure. The entire calculation is based upon electronic interactionRead more
The using simulation (first principle calculation) it possible to find the free energy of aluminum in bcc, fcc, hcp phase. Once you get the output you will see that the fcc structure has lowing energy compared to other possible structure. The entire calculation is based upon electronic interaction of aluminium atoms with each other.
See lessThe FCC Al will have less lattice energy than Bcc Al . A system will always tries to form to its minimum energy configuration
The FCC Al will have less lattice energy than Bcc Al . A system will always tries to form to its minimum energy configuration
See lessLiquid has short range order. In this short range order small cluster are there. These cluster has fcc crystal structure because of lowest free energy compare to other crystal structure
Liquid has short range order. In this short range order small cluster are there. These cluster has fcc crystal structure because of lowest free energy compare to other crystal structure
See lessLiquids have short range order
Liquids have short range order
See lessIn liquids, Small groups are present which have short range order is called clusters. These liquid clusters will have the similar crystal structure of that of the solid. While solidifying these clusters grouped together to form a nuclei which is having FCC crystal structure.
In liquids, Small groups are present which have short range order is called clusters. These liquid clusters will have the similar crystal structure of that of the solid. While solidifying these clusters grouped together to form a nuclei which is having FCC crystal structure.
See lessFcc structure of Al has less free energy than bcc structure. Hence Al gets fcc structure after cooling
- Fcc structure of Al has less free energy than bcc structure. Hence Al gets fcc structure after cooling
See lessDuring solidification, metals form clusters. These clusters exist because of short range orders in liquid. Clusters posses the crystal structure of least lattice energy because it is stable. Al have less lattice energy in FCC rather than in BCC. So it get backs to its crystal structure
During solidification, metals form clusters. These clusters exist because of short range orders in liquid. Clusters posses the crystal structure of least lattice energy because it is stable. Al have less lattice energy in FCC rather than in BCC. So it get backs to its crystal structure
See lessIn liquid state of there will be clusters of atom having fcc crystal structure will be present.As the temperature approaches freezing point number of FCC clusters and no of atoms in clusters increases. The larger size clusters become nuclei when they attain a critical size.
In liquid state of there will be clusters of atom having fcc crystal structure will be present.As the temperature approaches freezing point number of FCC clusters and no of atoms in clusters increases. The larger size clusters become nuclei when they attain a critical size.
See lessAs everyone said that.. No of physist botherd about what is the ground structure of a element or a component? Ground state must have low free energy to be stable. So FCC STRUCTURE posses low free energy then BCC ( IT IS ULTIMATELY FREE ENERGY)
As everyone said that.. No of physist botherd about what is the ground structure of a element or a component?
Ground state must have low free energy to be stable.
So FCC STRUCTURE posses low free energy then BCC
( IT IS ULTIMATELY FREE ENERGY)
See lessLiquid has short range order where the previous structure remains as small clusters all over the liquid. As Al is Fcc, it's liq has Fcc clusters in it and while solidification, those clusters grew attaining stability satisfying the conditions. So eventually attains it's Fcc
Liquid has short range order where the previous structure remains as small clusters all over the liquid. As Al is Fcc, it’s liq has Fcc clusters in it and while solidification, those clusters grew attaining stability satisfying the conditions. So eventually attains it’s Fcc
See lessWhen the liquid aluminum cooled to lower temperatures, tiny solid clusters are formed in the liquid. These are formed in such a away that contains minimum free energy within the solid cluster, for aluminum, fcc has the lowest possible free energy than bcc or hcp. So these tiny solid clusters will grRead more
When the liquid aluminum cooled to lower temperatures, tiny solid clusters are formed in the liquid. These are formed in such a away that contains minimum free energy within the solid cluster, for aluminum, fcc has the lowest possible free energy than bcc or hcp. So these tiny solid clusters will grow and turn into grains.
See lessLiquid has a short range order where small clusters have a periodic arrangement of atoms. These clusters can be of any crystal structure(FCC,BCC,HCP etc.). During solidification nucleation starts by formation of embryos(Clusters of atoms) which grows to critical size to become a nuclei. The clusterRead more
Liquid has a short range order where small clusters have a periodic arrangement of atoms. These clusters can be of any crystal structure(FCC,BCC,HCP etc.). During solidification nucleation starts by formation of embryos(Clusters of atoms) which grows to critical size to become a nuclei. The cluster (FCC,BCC,HCP) which have a lowest free energy becomes stable and starts to grow to become a nuclei.
See lessthe reason is free energy. at temperatures lower than melting point the free energy of FCC phase is the lowest. so the liquid has to transform to FCC and not bcc
the reason is free energy. at temperatures lower than melting point the free energy of FCC phase is the lowest. so the liquid has to transform to FCC and not bcc
See less