Effect of In Situ Reaction Temperature on the Microstructure and Mechanical Properties of 3 wt.% ZrB₂/A356

In-situ particle reinforced aluminum matrix composites are the research focus on the field of aluminum matrix composites. In this paper, 3 wt.% ZrB₂/A356 was prepared by in-situ reaction of A356-K₂ZrF₆-KBF₄ system with mechanical agitation at different reaction temperatures of 850, 870 and 890 °C, respectively. XRD and EDS analysis show that 3 wt.% ZrB₂/A356 particle reinforced aluminum matrix composite was successfully synthesized. According to this reaction principle, the feasibility of the reaction system was calculated by thermodynamics. By PC, SEM and TEM, the microstructure and distribution of the matrix and reinforcement were observed. Analysis of the experimental data shows that with the increase in reaction temperature, the grain refinement effect is better. When the reaction temperature is 890 °C, the grain size of aluminum matrix is the smallest, about 90 μm. With the increase in reaction temperature, the number of Al₃Zr decreased and the number of ZrB₂ particles increased gradually. When the reaction temperature was 890 °C, Al₃Zr disappeared completely and ZrB₂ particles were most evenly distributed. According to the growth and distribution of ZrB₂ enhanced particles, the corresponding model is proposed to the first time, and the mechanism is analyzed through the intuitive model diagram. The mechanical properties of 3 wt.% ZrB₂/A356 were studied.