常圧及び加圧焼結のメカニズムとニヤネットシェイプ制御 Ｎｉ３Ａｌ金属間化合物の燃焼合成時の燃焼温度，化合物生成量ならびに発生液相量の解析

Abstract

Combustion synthesis process has been taken an interest in new synthesizing technology of intermetallic compound. However, the synthesized products tend to be porous and the process is not used practically. To realize the process, a method of synthesizing the dense product should be developed. In my previous paper, fabrication of Ni3Al intermetallic compound by pressureless combustion synthesis process was investigated. Consequently, it was found that density of the synthesized compound depended on initial powder particle sizes, and the nearly full dense product was obtAlned in case of using fine powders as initial substances. However, cause of the densification or mechanisms of the shrinkage have not been known. In this paper, numerical analysis of the process of Ni3Al was performed to clear the relationship between the densification and the compound formation stages in the combustion.A Ni/Al compact which burned by the thermal explosion was divided into infinite elements, a numerical analysis model of combustion synthesis was derived under consideration of heat balance and material balance equations around the elements. The model was solved by LA.D. method, and the combustion synthesis behavior was analyzed.The compound formation behavior during the combustion synthesis was able to be simulated. From the calculation, it is found that large quantities of liquid phases were formed in the Ni3Al synthesis. In the previous experiments of the combustion synthesis, the rapid shrinkage was observed during extremely short times. The quick densification might be caused by the large quantities of the liquid phases.