Nacre-inspired lightweight and high-strength AZ91D/Mg2B2O5w composites prepared by ice templating and pressureless infiltration
We developed a facile and low-cost approach to prepare lightweight and high-strength magnesium–matrix composites with a nacre-inspired laminated structure. First, lamellar Mg2B2O5 whisker (Mg2B2O5w) scaffolds with initial solid loadings of 10, 15 and 20 vol% were prepared by ice templating. The wettability between a molten AZ91D alloy and the Mg2B2O5w scaffold was greatly improved by the incorporation of nano-SiO2 sol in the aqueous slurry, making the preparation of nacre-mimetic AZ91D/Mg2B2O5w composite by way of pressureless infiltration feasible. The SiO2 content in the Mg2B2O5w scaffold has a significant effect on the processing and the microstructure and properties of the composites. The optimum SiO2 content was about 6–8 wt% of the total ceramic loading. A lower SiO2 content resulted in incomplete infiltration, while a higher content led to the formation of a large quantity of Mg2Si in the composite. The flexural strength of the composites seemed independent of the initial ceramic loading (10–20 vol%), whereas the compressive strength and elastic modulus increased considerably and the crack-growth fracture toughness decreased with increasing ceramic content. The mechanism for such variations was addressed.
This work is supported by the National Natural Science Foundation of China (No. 51571099), the National Key R&D Plan (No. 2017YFB0703101) and the Changbai Mountain Scholars Program of Jilin Province (No. 2015011).
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Conflict of interest
The authors declared that they have no conflicts of interest to this work.