Article Type : Research Article
Authors : Run Xu
Keywords : Modelling; Dentritic; Cooling rate; Secondary arm space; Composition; Solidification; TiAl
It is seen that the higher constitutional
cooling represents higher cooling rate. The cooling rate will increase when the
composition increases. The cooling rate will increase from 4.5K/s to 8K/s when
the composition Al increases from 0 to 100% under the constitutional
temperature to be 30K. Meanwhile the bigger constitutional cooling causes
smaller dendritic secondary arm space. The dendritic secondary arm space will
decreases if composition increases too. The results are that the cooling rate
increases from 4.1K, 4.7K to 5K if the constitutional cooling is from 100K,
200K to 300K respectively. The arm space will decrease from 10.2?m, 10?mK,
9.5?m to 9?m when the composition is 0 and then arm sapce will decrease from
5.5?m, 5.3?m, 5?m to 4.5?m when the composition is 100% under constitutional
cooling increasing from 50K, 100K, 200K to 300K respectively.
The temperature and
composition with constitutional supercoiling has been important in
solidification of metal in materials research. So that the modelling on
relationship between them are established to study the parameters on them in
detail is significant in materials research and development. 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
experiment and practice well so the further search is been studied to look
forwards to anticipating good effectiveness to instruct practice [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 about the solid and liquid line the constitutional super cooling 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 supercoiling is formed by solute redistribution to cause solute
concentration change in front of solid and liquid interface which causes to
change theoretical solidification temperature for forming the super cooling in
interface liquid. The final problem in constitutional super cooling is the
temperature difference which can attain the effectiveness directly and clearly.
Whether the result fits to practice and how it fits has been one that affects
the final destination in this research. From
line equation the cooling and constitutional super rcooling 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
supercoiling benefits to the cooling course since its high temperature so the
way to choose reasonable value is necessary. In this paper the dendritic
secondary arm space is searched for constitutional super cooling which is our
destination. How has it affected the cooling rate and dendritic secondary arm
space, which is important? Because the three parameters is important in
solidificative course it needs to be further searched that is necessary and
significant.
The curve is drawn according to modelling as below. Two parts are included. One is curve between cooling rate and composition and the other is the one between dentritic secondary arm spaces. As seen in Figure 1(a~d) the cooling rate will increase from 4.5K/s to 8K/s when the composition Al increases from 0 to 100% under the constitutional temperature to be 30K. The results are as below. The cooling rate increases from 4.4K, 4.7K to 5K if the constitutional cooling is from 100K, 200K to 300K respectively. The cooling rate will increase from 8.2K to 10K with increasing constitutional cooling increases from 100K to 300K. It expresses that the higher constitutional cooling represents higher cooling rate (Figure 1).
(a) T; ?T=30K
(a) T; ?T=100K
(a) T; ?T=200K
(a) T; ?T=300K
(a) L; ?T=50K
(a) L; ?T=100K
(a) L; ?T=200K
(a) L; ?T=300K
Figure 1: The relationship between the cooling rate and dentrite secondary arm space with composition under different constitutional super cooling.
As seen in Figure 1(e~h)
the secondary arm space in dentrite will decrease too from 10.2?m to 5.5?m with
increasing composition from 0 to 100%. The arm space will increase from 10.2?m,
10?mK, 9.5?m to 12.2?m when the composition is 0 and then arm sapce will
increase from 6?m, 6.5?m, 6.8?m to 9?m when the composition is 100% under
constitutional cooling increasing from 50K, 100K, and 200K to 300K
respectively. It explains the bigger constitutional cooling cause’s smaller
dendritic secondary arm space. In general from Figure 1(a~h) the cooling rate
and dendrite secondary arm space has not been big which is about 1K/s and 0.5?m
respectively. So it is speculated that the constitutional super cooling is a
certain value. Since the matrix value is 10.2K/s and 10?m which is general
value to compare with difference caused by constitutional super cooling.
It is seen that the
higher constitutional cooling represents the higher cooling rate. The cooling
rate increases with increasing composition. Meanwhile the bigger constitutional
cooling causes smaller dentritic secondary arm space. The dentritic secondary
arm space will decrease too with increasing composition. The cooling rate and
dentrite secondary arm space has been small which is about 1K/s and 0.5?m
respectively. So it is speculated that the constitutional supercooling is a
certain value. Since the matrix value is 10.2K/s and 10?m which is small too to
compare with difference caused by constitutional supercooling.
This work was supported
by the Korea of Science and Engineering Fund, under the Specified Base program?96-0300-11-01-3.