The AI-AIN-Si composites were prepared in the gas-in-liquid in situ synthesized flow-reaction-system, which was implemented by a powder metallurgy and reaction sin- tering route. The experimental results showed that A...The AI-AIN-Si composites were prepared in the gas-in-liquid in situ synthesized flow-reaction-system, which was implemented by a powder metallurgy and reaction sin- tering route. The experimental results showed that A1-AIN- 50SiB material （prepared by ball-milling powders） and AI- AIN-50SiM material （prepared by mixing powders） exhibited the semi-continuous Si structures and the isolated Si islands, respectively. Subsequently, the AI-AIN-50Si materials were selected as the model materials by phase identification and microstructure analysis. The dynamic microstructural evolu- tion of AI-AIN-50Si materials was investigated using the computational fluid dynamics （CFD） method. Mathematical models and simulation results showed that the in situ synthesis of AIN was strongly influenced by the structure and the flow- path （（Cg,N2/lg,N2）＋（Cs,AlN/ls,AiN））. The flow paths of AI-AIN-50Si^B material were restricted by the semi-continuous Si. These Si structures can promote the formation of the strong turbulence with gradually weakened fluctuation, so that the in situ synthesis of AIN was interconnected and surrounded by an interpenetrating Si network. In contrast, the flow paths of AI- AIN-50Si^B material can easily pass through the isolated Si due to its mild turbulence with linear relationship. As a result, AIN was separated by the isolated Si and agglomerated in the matrix. Overall, the present work provides new insights into dynamic microstructural evolution in in situ reaction sinter- ing systems.展开更多
基金supported by the financial support of the National Natural Science Foundation of China (51171146 and 51101177)the Program for Key Science and Technology Innovative Research Team of Shaanxi Province (2013KCT-05)
文摘The AI-AIN-Si composites were prepared in the gas-in-liquid in situ synthesized flow-reaction-system, which was implemented by a powder metallurgy and reaction sin- tering route. The experimental results showed that A1-AIN- 50SiB material （prepared by ball-milling powders） and AI- AIN-50SiM material （prepared by mixing powders） exhibited the semi-continuous Si structures and the isolated Si islands, respectively. Subsequently, the AI-AIN-50Si materials were selected as the model materials by phase identification and microstructure analysis. The dynamic microstructural evolu- tion of AI-AIN-50Si materials was investigated using the computational fluid dynamics （CFD） method. Mathematical models and simulation results showed that the in situ synthesis of AIN was strongly influenced by the structure and the flow- path （（Cg,N2/lg,N2）＋（Cs,AlN/ls,AiN））. The flow paths of AI-AIN-50Si^B material were restricted by the semi-continuous Si. These Si structures can promote the formation of the strong turbulence with gradually weakened fluctuation, so that the in situ synthesis of AIN was interconnected and surrounded by an interpenetrating Si network. In contrast, the flow paths of AI- AIN-50Si^B material can easily pass through the isolated Si due to its mild turbulence with linear relationship. As a result, AIN was separated by the isolated Si and agglomerated in the matrix. Overall, the present work provides new insights into dynamic microstructural evolution in in situ reaction sinter- ing systems.
