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Título:
SOLIDIFICATION, MACROSTRUCTURE AND MICROSTRUCTURE ANALYSIS OF AL-CU ALLOYS DIRECTIONALLY SOLIDIFIED FROM THE CHILL FACE
Autor/es:
ALICIA ESTHER ARES; CARLOS ENRIQUE SCHVEZOV
Lugar:
San Francisco, California. USA
Reunión:
Simposio; SHAPE CASTING: THIRD INTERNATIONAL SYMPOSIUM; 2009
Institución organizadora:
The minerals, Metals and Materials Society
Resumen:
The understanding of  the phenomenon of  the Columnar  to Equiaxed Transition  (CET)  is very important  for  metallurgical  applications.  In  the  present  study  the  CET  was  observed  in aluminum-copper  alloys  of  different  compositions  (Al-2wt%Cu,  Al-20wt%Cu  and  Al-33.2wt%Cu, which were solidified directionally from a chill face. The main parameters analyzed include  cooling  rates,  temperature  gradients,  solidification  velocities  of  the  liquidus  fronts, recalescence, grain size, primary and secondary dendritic arm spacing and eutectic spacing. The temperature gradient and  the velocity of  the  liquidus  front  reach  low critical values before  the transition. These critical values are between 0.4 to 3.8 mm.s-1 for the velocity and -0.44 to 0.10 K.mm-1 for  the  temperature  gradient.  In  the  case  of  the  eutectic  alloys,  the  transition  from columnar  to  equiaxed  occurs  with  similar  characteristics  as  for  the  other  concentrations,  the resultant  lamellar,  rod-like  or mixed  solidification microstructure  have  parameters which  also depend on solidification conditions, mainly velocity.