Shape of the in-situ (Al, Zn)-Ti reinforcing particles and their influence on structure and structural stability of selected Zn-Al and Al-Zn cast alloys

Abstract

Abstract The foundry engineering still needs new cast materials of improved properties. These can be achieved by elaborating completely new alloys and metal matrix composites or by elaborating the alloys/composites basing on the already very well-known matrixes. The good example of the latter solution are high-aluminium zinc (H-Al Zn) and high-zinc aluminium cast alloys (H-Zn Al). Both of these groups show good damping and strength properties but rather low ductility and insufficient structural (and dimensional) stability, caused by long term transformation of the Cu-containing bearing phases. The performed works were devoted, among others, to building composites of improved structural stability reinforced with ternary (Al, Zn)-Ti aluminides. The in-situ reinforcement was built by needle-shape ternary aluminides based on the DO22 TiAl3 binary phase introduced with AlTi-based master alloys or by compacted semi-globular ones based on the L12 Zn3Ti particles introduced with a ZnTi-based master alloy. The mentioned particles substitute partly or totally for Cu-based bearing phase and the influence of this substitution on the structural stability and tribological properties is also discussed in the paper.