Influences of in-situ ZrB2 and TiB2 particles on Portevin-Le Chatelier effect for AlSi9Cu1 alloy

In this paper, the plastic instability phenomenon Portevin-Le Chatelier effect (PLC) was investigated in AlSi9Cu1 alloy and the in-situ (ZrB2+TiB2)/AlSi9Cu1 composites fabricated from the Al-K2TiF6-K2ZrF6-KBF4 system. Microstructure observation and X-ray diffraction testing revealed that the ZrB2 and TiB2 particles were generated via direct melting reaction. Mechanical property testing showed that 3 wt.% (ZrB2+TiB2) particles reinforced composites owned the highest ultimate tensile strength (226 MPa). Meanwhile, the effects of mass fraction of reinforced particles, strain rate on the critical strain were also systematically studied. The results indicated that both normal and inverse behavior of critical strain vs. strain rate existed during the tensile deforming for AlSi9Cu1 alloy and (ZrB2+TiB2)/AlSi9Cu1 composites.