Prakt. Met. Sonderband 41 (2009) 283 
The influence of modification for structure and fracture morphology 
of alloy AISi6Cu4 
F. Romankiewicz, R. Romankiewicz. 
University of Zielona Gora 
1 Introduction 
Alloy AlSi6Cu4 is used in casts of complicated shapes and diversified widths of walls. It is 
he grain boundaries frequently used in thin-wall casts working under medium, or sometimes higher loads. An important 
feature of the alloy is the fact that it may be produced from Al-Si and Al-Cu scrap alloys [1]. 
The structure and the mechanical properties of AlSi6Cu4 alloy may be improved through applying 
thermal treatment or a simple technological modification with suitable micro-additives. 
To achieve the advantageous state of the structure of A1Si6Cu4 alloy requires a modifying process 
Twt.% La alloy. involving refinement of the dendrites of the primary o-phase as well as the change of the 
nd solidification morphology of the eutectic silicon from lamellar into fibrous [2-5]. 
iced by the rapid The authors have tried to modify AlSi6Cu4 alloy applying AlTi5B1 master alloy to refine the a- 
w possibility for phase dendrites, whereas AlSr10 master alloy is used to refine the eutectics. It has been recognised 
that it is purposeful to investigate the influence of modification of A1Si6Cu4 silumin on its structure 
a alloy by melt- and morphology of fractures in an impact resistance test. 
neous dispersion 
he refinement of 
ng suitable oxide 
f int talli ee . 
of mfermetatiic 2 Description of the experiments 
2.1 Melting and modification of AlSi6Cu4 alloy 
The experiments were carried out for the AlSi6Cu4 technical alloy, of the chemical composition 
conforming to Polish Standards PN-76/H-88027. The melting process and the modification were 
carried out in a graphite-chamotte melting crucible in a chamber oven. 
Table 1. The influence of the modification process of the AlSi6Cu4 impact resistance. 
Cast Nr Modification conditions Impact resistance 
_ [J/em?] 
Aedermannsdorf. 1 Without modification 3,6 
2 Modified with 0,2% AITi5B1 3 4,3 
3 Modified with 0,3% AITi5B1 6,1 
4 Modified with 0,2% AISr10 7 6,4 
5 Modified with 0,3% AISr10 N 6,9 
6 Modified with 0,2% AITi5B1 and 0,3% AlSr10 7,0 | 
7 Modified with 0.3% AITi5B1 and 0,3% AlSr10 6.0