Comparison of rheological behavior between semisolid mixtures of ZA27 alloy and ZA27-AL2O3 composites

Abstract

The rheology of semi-solid mixtures (SSMs) of ZA27 composite strengthened by Al2O3 particles with different size and weight fraction has been investigated and compared to that of the matrix ZA27 alloy. The influence of processing variables on the rheological behavior of SSMs was examined. The mixing power change of SSMs was determined by the "electric method“ in the temperature range from 479 to 440°C, at constant cooling rate. Mixing of ZA27 alloy SSM was carried out using cylindrical and paddle stirrers, while SSMs of composites were mixed using paddle stirrer only. On the basis of experimental measurements applying “electrictric method” the values of apparent viscosity were calculated. The values of apparent viscosity for SSMs of composites are lower than those for the matrix ZA27 alloy SSM in the whole range of examined temperatures. It was noticed that apparent viscosity of SSMs of composites containing small Al2O3 particles is higher comparing to that of composites with large Al2O3 particles.