Article Type : Research Article
Authors : Xu R, Nam T, Hyo Jun A, Reddy NS, Kim K and Kim Y
Keywords : Modelling; Relationship; Temperature; Gibbs free energy; Composition; Solidification; Constitutional supercooling
The temperature difference ?T decreases
from 0 to 190K if composition difference ?Com increases from 0 to 0.18
respectively. The temperature decreases with increasing constitutional supercooling.
The temperature decreases with increasing ?T. The temperature changes from
2,250K to 1,300K in ?T=30K, meanwhile it decreases from 2,250K to 2180K with
the constitutional supercooling increasing from 30K to100K. With increasing
constitutional supercooling ?T from 30K, 100K, 200K, 300K to 400K the free
energy will be lower from -3,300J, -3,600J, -3,800J, -4,200J to -4,400J. It
means that with increasing constitutional supercooling the easy solidification
will be formed.
The temperature and
composition with constitutional supercooling has been important in
solidification of metal. So that the modelling on relationship between them are
established to study the parameters on them in detail is significant in
materials research. For the convenience the data adopted from phase diagram and
experience to ensure the correction of them. The result has been found to be
consistent with the practice well so the further search is been studied to look
forwards to anticipating good effectiveness [1-9]. As we know the
constitutional cooling is the important cooling which is different to usual
cooling Therefore the related search will be proceeded to find its role on
solidification of metal. When it attains near the solid and liquid line the
constitutional supercooling will be formed to drive the nuclear crystal to
form. So it is important at the solidification course in special the original
solidification to new crystal. Constitutional supercooling is formed by solute
redistribution to cause solute concentration change in front of solid and
liquid interface which causes to change theory solidification temperature for
forming the super cooling in interface liquid. From line equation the cooling
and constitutional super cooling has been formed through phase diagram method.
The constitutional cooling is checked through chart to find the difference with
its change. As we knew the constitutional supercooling benefits to the cooling
course since its high temperature the way to choose reasonable value is
necessary.
It is searched that relationship between composition difference from 0 to 0.2 and temperature difference firstly. Then the chart between the temperature and composition from 0 to 1 with constitutional supercooling. At last the Gibbs free energy with Al composition under different constitutional supercooling like 30K, 100K, 200K, 300K and 400K is been studied. The details discussion is as below (Figure 1).
Figure 1: The relationship between temperature difference and composition difference in TiAl alloy.
(a) ?T=30K
(a) ?T=100K
(a) ?T=30K
(a) ?T=100K
(a) ?T=200K
(a) ?T=300K
(a) ?T=400K
Figure 3: The chart on Gibbs free energy and composition with constitutional super cooling ?T in TiAl.
As seen in Figure 1 the
temperature difference ?T decreases from 0 to 190K if composition difference
?Com increases from 0 to 0.18 respectively. In general the composition scope
arranges from 0.01 to 0.12 so the ?T arranges from 10K to 120K in TiAl alloys
according to the modelling. As seen in Figure 2 the temperature decreases with
increasing constitutional supercooling. The temperature decreases with
increasing ?T. The temperature changes from 2,250K to 1,300K in ?T=30K,
meanwhile it decreases from 2,250K to 2,180K with the constitutional
supercooling increasing from 30K to100K (Figure 2,3).
As seen in Figure 3 the Gibbs free energy difference will increase when composition Al increases in Ti-Al. Furthermore with increasing constitutional supercooling ?T from 30K, 100K, 200K, and 300K to 400K the free energy will be lower from -3,300J, -3,600J, -3,800J, -4,200J to -4,400J. It means that with increasing constitutional supercooling the easy solidification will be formed. Therefore the higher ?T will promote the speed of solidification in Ti-Al. In detail with changing from-1,600J to -700J with changing Al from 0 to 1 in constitutional supercooling ?T =400K. It is better situation since low energy.
The temperature
difference ?T decreases from 0 to 190K if composition difference ?Com increases
from 0 to 0.18 respectively. The temperature decreases with increasing
constitutional supercooling. The temperature decreases with increasing ?T. The
temperature changes from 2,250K to 1,300K in ?T=30K, meanwhile it decreases
from 2,250K to 2180K with the constitutional supercooling increasing from 30K
to100K. With increasing constitutional supercooling ?T from 30K, 100K, 200K,
300K to 400K the free energy will be lower from -3,300J, -3,600J, -3,800J,
-4,200J to -4,400J. It means that with increasing constitutional supercooling
the easy solidification will be formed.