INVESTIGATION ON THE CRYSTAL-STRUCTURE OF THE EUTECTIC SOLIDIFICATIONFRONT IN AN ALSI11 ALLOY

The crystal growth and orientation relationship Of alpha(Al) and Si ph ases were investigated during eutectical crystallization. Pure AlSi-al loy with 11 wt.% Si was unidirectionally solidified. The solidificatio n front (SF) was stopped by quenching, and the liquid phase in front o f the SF was frozen. By this, the kinetics of the crystal growth can b e investigated directly at the SF, in the unidirectionally solidified volume in different distances from the SF and the frozen liquid phase in front of the SF. At the SF the difference in orientation of the alp ha(Al) and the Si phases is between 5 and 7-degrees with the orientati on relationship (111BAR)Si \\ (111BAR)Al. This distinct epitaxy disapp ears in the unidirectionally solidified volume with increasing distanc es from the SF. In front of the SF the TPRE growth of the Si phases is supported by a helix-like from the points of nucleation at the (111) twin planes.