Columnar-To-Equiaxed Transition In Metal Matrix Composites

145. ALICIA E. ARES ; CARLOS E. SCHVEZOV

San Antonio, TX

Congreso; TMS 2013. 142st ANNUAL MEETING & EXHIBITION-Materials Processing Fundamentals.; 2013

TMS

The present work is focused on the study of the effect of the directional heat extraction on the SiC distribution in the zinc-aluminum matrix composite (MCMM) and on the columnar ? to ? equiaxed (CET) position in samples directionally solidified. ZA-27 alloy matrix isreinforced/filled with ceramic-particulates of Silicon-carbide (SiC), vertically directionally solidified and the following parameters were measured: cooling rates, temperature gradients, interphase velocities and the influence of them on the solidification microstructure of the MCMM is analyzed. The recalescence was detected and measured during the equiaxed transition being of the order of 3.5°C to 1.1°C. The values of the temperature gradients reached minimum during the CET in most cases even negative (between -3.89 K to 0.06 K). The interphase velocities vary between 0.07 to 0.44 mm/s at the transition. Also, the presence of ceramic particles in ZA27 alloys affects the thermodynamic local conditions and the kinetic of nucleation producing a finer microstructure.