An example: Characterisation of solidified microstructure of Al-4wt%Cu alloy 
la fro , . 
te compe 9 Experimental details 
Cellular, Cellular 8 . 
Ue ge po Al-4wt%Cu alloy (size @6x100mm) was melted in a four-zone resistance heated Bridgman type 
fle sgn * furnace [1]. Temperatures of zones were adjusted to 800, 750, 700 and 650°C to produce a 
12 ams cp by temperature gradient on the furnace wall. The furnace temperature was controlled by four 
1 Can be rou thermocouples located in the furnace tube. The specimens were inserted into a graphite bar, which 
fic mer was placed inside a silica tube. After melting the probes were moved downward into the water 
—_ ie placed under the furnace. Six thermocouples (NiCr-Ni) in the graphite rod around the sample 
meu recorded the temperature during the solidification. A computer program was worked out to calculate 
orimary ni the temperature gradient and solid/liquid interface velocity values from the measured temperature 
Co data. The moving velocities (v) were 5x10, 2x10* and 8x10“ m/s. The calculated interface 
¢ tied ff velocities (5.1x10°%, 2.1x10%, 7.9x10™* m/s) were very similar to the moving velocities. The 
ms hd i calculated temperature gradient at the solid/liquid interface (Gy) was 1500 K/m. The sketch of the 
NE ho experimental equipment can be seen in Fig. 1. 
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scribed above § 
solution) can be Furnace tube | ~ontrol 
e instead of the . 
Graphite bar thermo 
— couples 
Al-Cu sample 
i. - Thermo- 
Silica tube ‘couples 
ation processes Cotton 
al (constrained) insulation 
ification heat is . 
eat Is extracted Water-cooling 
tonian cooling). © 
onstant (steady- “A 
wsibility of the oF 
SCN-Acetone ' Water in 
interrupted and / 
ie Water out ~ - pe 
Fig. 1: Sketch of the unidirectional solidification equipment 
The lattice of the 
‚he phases can be 
x of dendritic 08 Solidification path 
je nas. Th . . . 
nd phases can b8 The solidification of specimens began with the formation of a solid solution dendrites. At the end 
of solidification non-equilibrium eutectic (a+ALCu) was formed between the primary and 
secondary dendrite arms (see Fig.5). The eutectic was degenerated in some cases; the a solid 
solution part of eutectic was solidified on the surface of a dendrite [2]. 
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