Real time investigation of the grain refinement dynamics in zinc alloy by synchrotron microradiography

The grain refining performance of titanium diboride particles in zinc alloy was investigated by adding in␣situ formed Al-TiB2 master alloy into ZA27 alloy. The results showed that TiB2 particles could significantly refine the structure of ZA27. After adding 1.1% TiB2, the average grain size decreased markedly from 205.4 μm to 65.8 μm. To characterize the mechanism by which TiB2 refines the grain size, synchrotron microradiography technique was used for the first time to investigate the effect of TiB2 on the grain nucleation and growth kinetics. Real-time observations revealed that TiB2 particles refine ZA27 by facilitating heterogeneous nucleation, enhancing dendrite fragmentation and constraining the dendrite growth.