Effect of processing temperature on the microstructure of Al-7Ti master alloy and on refinement of  α-Al dendrites in Al-7Si alloys 

Virupaxi Auradi1*, Shivaputrappa Amarappa Kori

1R & D Centre, Dept. of Mech. Engg, Siddaganga Institute of Technology, Tumkur 572 103, Karnataka, India

2R & D Centre, Dept. of Mech. Engg., Basaveshwar Engineering College, Bagalkot 587 102, Karnataka, India

Adv. Mater. Lett., 2015, 6 (3), pp 252-259

DOI: 10.5185/amlett.2015.5646

Publication Date (Web): Feb 22, 2015

E-mail: vsauradi@gmail.com

Abstract


The present work aims at evaluating the grain refining performance of Al-7Ti master alloys with different microstructures on Al-7Si alloys. Al-7Ti master alloys were prepared in an induction furnace by salt route involving the reactions between K2TiF6 and molten Al. Reaction temperatures chosen for producing Al-7Ti master alloys were 800oC, 900oC and 1000oC while reaction time was kept constant at 60min. These indigenously prepared master alloys at different temperatures were characterized by chemical analysis; particles size analysis, XRD and SEM/EDX microanalysis. Results of particle size analysis suggest that mean size of Al3Ti intermetallic particles in Al-7Ti master alloys were increased from 15.8µm to 22.4 µm as temperature is increased from 800oC-1000oC. SEM/EDX studies revealed fine blocky morphology, large blocky and flaky/petal morphologies of Al3Ti intermetallic particles in Al-7Ti master alloys at 800oC, 900oC and 1000oC respectively. Results of grain refinement studies suggest that Al-7Ti master alloy prepared at reaction temperature of 800oC shows better grain refinement performance on Al-7Si alloy when compared to the Al-7Ti prepared at 900oC and 1000oC. In future, the influence of reaction time on microstructural and grain refining behaviour of Al-7Ti master alloys will be evaluated and the performance of these Al-7Ti master alloys will be compared with Al-B and Al-Ti-B master alloys.

Keywords

Master alloy, grain refinement, Al-7Si alloy, microstructure.

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