Influence of in-situ TiB2 particles on microstructure and mechanical properties of ZL101A alloy

In-situ TiB2p/ZL101A composites were successfully prepared by the salt-metal reactions. The study investigated the influence of TiB2 particle content on the microstructure and mechanical properties of the TiB2 particlereinforced ZL101A alloy in the as-cast state. The results showed that with an increase in TiB2 particle content, the microstructure of the composite exhibits significant refinement. Specifically, the 3 wt% TiB2p/ZL101A composite showed the optimal microstructure, with alpha-Al grains and eutectic Si particles size reduced by 53 % and 78 %, respectively. This can be attributed to the influence of TiB2 particles on grain growth and the quantity of heterogeneous nucleation during solidification process. In addition, the 3 wt% TiB2p/ZL101A composites showed excellent integrated mechanical properties, with the ultimate tensile strength, yield strength and hardness of 194.5 MPa, 95.9 MPa and 71.06 Hv, respectively. The contributions of each mechanism to the yield strength (YS) increment were calculated by the YS strengthening mechanism and the modified shear-lag model. It is seen that a satisfactory agreement between with the measured and calculated, with the thermal mismatch strengthening (CTE) being the main contributor to the YS increment in TiB2p/ZL101A composites, while the load-bearing strengthening (Load), the grain refinement strengthening (Hall-Petch) and the Orowan strengthening mechanisms (Orowan) contributed minimally.