Prakt. Met. Sonderband 41 (2009) 285 
erature 1003 K 
ty were applied 
on process lasted 
esented in Table 
in is presented in 
recipitation of 
5B1 master 
bhase dendrites 
ie AlSr10 master 
the eutectic 
inement of the 
larly for 0,3% 
the complex 
(Fig. 1f) as well 
Fig. 1 Microphotography of the zone of the profile of the fracture of the AlSi6Cud 
alloy: 
a) ron-modified. b) modified with 0,2% AITi5B1, ¢) modified with 0,3% 
AlTi5B1, d) modified with 0,2% AlSr10, e) modified with 0,3% AlSr10, f) 
modified with 0,2% AlTi5B1 and 0,3% AlSr10, g) modified with 0.3% 
AITi5B1 and 0.3% AlSr10 
The surfaces of the fractures of the AlSi6Cu4 alloy are presented in the scanned microphotographs 
(Fig. 2). They imply that the samples of the non-modified alloy (Fig. 2a) as well as the one after the 
modification process with the AITi6B1 master alloy (Fig. 2b and 2c) are characterised by a fissile 
fracture. The samples of the silumin after the modification with the AISr10 master alloy (fig. 2d and 
2e) as well as the ones after the complex modification (fig. 2f and 2g) are characterised by a 
considerably increased contribution of the surface of the plastic fracture. 
The observed changes of the structure of the A1Si6Cu4 alloy are consistent with the results of the 
impact resistance tests (Table 1). The non-modified alloy revealed the impact resistance amounting 
3,6 J/cm. The modification of the silumin with the additives 0,2 and 0,3% AITi5B1 (casts 2 and 3) 
resulted in the increase in the impact resistance to the level 4,3-6,1 J/cm”. The modification of the 
alloy with the additives 0,2 and 0,3% AlSr10 (casts 4 and 5) provided the further increase in the 
resistance to the level 6,4-6,9 J/cm”. The highest increase in the impact resistance of the AlSi6Cu4 
silumin, to the level 7 J/cm?, has been obtained after the modification with the additives 0,2% 
AlTi5B1 and 0,3% AlSr10 (cast 6). The increase in the additive AITi5BI to the level 0,3% (cast 7). 
for the complex modification, resulted in the decrease in the impact resistance of the silumin to 6 
Jem”