Investigation of the high-aluminium zinc alloys grain refinement process due to Ti addition

The paper comprises results of examination of the Zn-25 wt % Al alloy grain refinement by the ZnTi4 modifying master alloy. On the basis of thermal an alysis, X-ray diffractometry, scanning electron microscopy and light micros copy it was stated that after modification the examined alloy shows a decre ase of the undercooling, significant refinement of macrostructure as well a s significant refinement of the primary dendrites of alpha' ZnAl solid solu tion. It was also stated that the ZnTi4 master alloy introduces L1(2) TiZn3 particles which act as substrate of the alpha' ZnAl solid solution heterog eneous nucleation. In the modified melt TiZn3 particles undergo transformat ion into Ti(Al, Zn)(3) particles which show L1(2) crystal structure and lat tice parameter very close to that of the alpha' phase. These features make the Ti (Al, Zn)(3) particles very effective substrate of the alpha' dendrit es nucleation.