Influence of Reaction Temperature and Reaction Time for the Manufacturing of Al-Ti-B (Ti:B = 5:1,1:3) Master Alloys and Their Grain Refining Efficiency on Al-7Si Alloys

摘要

In the present work, ternary Al-Ti-B master alloys have been prepared in an induction furnace by the reaction between preheated halide salts (K_2TiF_6 and KBF_4) and liquid molten Al. A number of process parameters such as reaction temperature (800, 900, 1,000 °C), reaction time (45, 60, 75 min.) and compositions (Ti/B ratio: 5/1, 1/3) have been studied. The indigenously prepared master alloys were characterised by chemical analysis, particles size analysis, XRD and SEM/EDX microanalysis. Results of particle size analysis suggest that the sizes of the interme-tallic particles [Al_3Ti and TiB_2 in Al-5Ti-lB and (Al, Ti)B_2 in Al-1Ti-3B] present in various Al-Ti-B master alloys increases with increase in reaction temperature (800-1,000 °C) and reaction time (45-75 min.). The pop ulation of the particles decreases with increase in reaction time and temperature. Further, SEM/EDX studies revealed that different morphologies of the intermetallic particles were observed at different reaction temperatures and reac tion times. Further, the performances of the above-prepared master alloys were assessed for their grain refining effi ciency on Al-7Si alloy by macroscopy, DAS analysis. Grain refinement studies suggest that, B-rich Al-lTi-3B masteralloy shows better grain refinement performance on Al-7Si alloy when compared to Ti-rich Al-5Ti-1B master alloy.