Highly pure Al_(4)SiC_(4) powders were prepared by carbothermic reduction at 2173 K using Al_(2)O_(3),SiO_(2),and graphite as raw materials.The obtained Al_(4)SiC_(4) powders owned hexagonal plate-like grains with a d...Highly pure Al_(4)SiC_(4) powders were prepared by carbothermic reduction at 2173 K using Al_(2)O_(3),SiO_(2),and graphite as raw materials.The obtained Al_(4)SiC_(4) powders owned hexagonal plate-like grains with a diameter of about 200-300μm and a thickness of about 2-6μm.Based on the experimental results,the reaction of Al_(4)SiC_(4) formation and grain evolution mechanisms were determined from thermodynamic and first-principles calculations.The results indicated that the synthesis of Al_(4)SiC_(4) by the carbothermic reduction consisted of two parts,i.e.,solid-solid reactions initially followed by complex gas-solid and gas-gas reactions.The grain growth mechanism of Al_(4)SiC_(4) featured a two-dimensional nucleation and growth mechanism.The gas phases formed during the sintering process favored the preferential grain growth of(0010)and(110)planes resulting in formation of hexagonal plate-like Al_(4)SiC_(4) grains.展开更多
基金the National Science Fund for Excellent Young Scholars of China(No.51522402)the National Natural Science Foundation of China(Nos.51572019 and U1460201)the Central Universities of FRF-TP-15-006C1 for financial support.
文摘Highly pure Al_(4)SiC_(4) powders were prepared by carbothermic reduction at 2173 K using Al_(2)O_(3),SiO_(2),and graphite as raw materials.The obtained Al_(4)SiC_(4) powders owned hexagonal plate-like grains with a diameter of about 200-300μm and a thickness of about 2-6μm.Based on the experimental results,the reaction of Al_(4)SiC_(4) formation and grain evolution mechanisms were determined from thermodynamic and first-principles calculations.The results indicated that the synthesis of Al_(4)SiC_(4) by the carbothermic reduction consisted of two parts,i.e.,solid-solid reactions initially followed by complex gas-solid and gas-gas reactions.The grain growth mechanism of Al_(4)SiC_(4) featured a two-dimensional nucleation and growth mechanism.The gas phases formed during the sintering process favored the preferential grain growth of(0010)and(110)planes resulting in formation of hexagonal plate-like Al_(4)SiC_(4) grains.
