Self-propagating Combustion Synthesis Of Al-ti-c Master Alloys Of The Dilution Process

Al-Ti-C master alloys used as grain refiners of the aluminum and its alloys have been prepared by Self-propagating high-temperature synthesis (SHS) using Al, Ti and graphite. The particles have appeared serious agglomeration in the synthesized grain refiners and can affect the grain refining performance. So Al-Ti-C by SHS has been diluted for rising its grain refining. In this paper, some effect of parameters for diluting have been researched, such as green-compact pressure, temperature and insulation time, and grain refining effects of Al-Ti-C was studied preliminarily. Grain refining performance of Al-Ti-C master alloys on industry pure aluminum was evaluated qualitatively, at the same time, compared with that of Al-5Ti-B grain refiners made in china and LSM respectively.The results are as follows: Green-compact pressure affected the microstructure of Al-Ti-C in the Self-propagating high-temperature synthesis, which would affect diluting. Combustion reaction was vehement and particles agglomeration was strong with the increase of green-compact pressure, liquid aluminum could dilute the agglomeration hardly for rising the refinement. If green-compact pressure was above 80MPa, Al-Ti-C had been diluted in aluminum hard, if it was below 60MPa, diluting was good, particularly in 20MPa, aluminum could dilute particles freely.. Temperature and insulation time in diluting also affected the result of Al-Ti-C refinement. If the temperature was low, Al-Ti-C would be stopped diluting aluminum liquid, otherwise, high temperature could induce some problem, for example, Al₃Ti of the shape of needle would appear and affect the refinement. If the time was short, particles agglomeration could not be diluted, on the contrary, the refining particles would become big size. Finally, the Al-Ti-C grain refiner had good refinement when the temperature was 800 ℃ and time was 15min. Ti in Al-Ti-C was wasted in the diluting. It was the reason that some particles was falling into diluted slag.The refining experiment shows: Al-Ti-C after diluting has good grain refining performance. Refining has been affected by TiC and Al₃Ti together.