| Al-Ti-C powder containing fluoride solvent is compacted to prepare Ti CP/Al by TIG melting in the graphite crucible. Appling OM, DSC, SEM, XRD and EDAX analytical methods to analyze the reaction thermodynamics and kinetics of Al-Ti-C system, dynamic model is established to analyze the formation process and mechanism of Ti C, the model also used to study the influence of technological arameters and fluoride solvent addition on the microstructure and morphology of the composites materials.The results showed that the reaction of Al-Ti-C system is a complex and continuous process.There are two kinds of transition phase in the reaction process, Al3 Ti and Al4C3. According to the related thermodynamic calculation, we set up Ti C formation kinetics model: in the Ti enrichment condition, Al3 Ti begins to decompose and release the molten titanium atoms, gathering around Al4C3, take this reaction : Al4C3(s) +3[Ti] → 3Ti C(s) + 4Al(l) to produce Ti C.The results showed that the existence form of Ti C in the composite Al-Ti-C system is Ti Cx, we get the crystal cell parameters corresponding to atomic ratio relationship, cystal cell parameter a increase with the atomic ratio x. The existenen conditions of titanium carbide ranged from Ti Cx2 to Ti Cx1. The x in Ti Cx actually decreases with temperature increasing.The current size and the ratio of prefabricated elements has a great influence to the Al-Ti-C system reaction and the distribution of the particles. When the ratio of Ti / C is 1:1, we can get small particles and distributed evenly Ti C particulate reinforced composite materials.In a certain range, along with fluoride solvent content increases, its influence on the porosity which exist in the composite materials is significant improvement. But when it reaches a certain amount, the role will no longer obvious, and the volume of the pore increases, the reason is that excessive solvent was stranded in the melt reaction generated in the impurities such as defects. |
PDF Full Text Request