Assessing Grain Refining Performance of Al–4B Master Alloys Produced Under Different Processing Conditions: Fid-Bau Portal

Assessing Grain Refining Performance of Al–4B Master Alloys Produced Under Different Processing Conditions

Auradi, V. / Bharath, V. / Nagaral, Madeva / Kori, S. A.

Current work aims at producing Al–4B grain refiners indigenously having different microstructures under different processing conditions by the effect between liquid Al and KBF₄ halide salt. Production temperatures of 800, 900 and 1000 °C and times of 45, 60 and 75 min were selected for processing of Al–4B refiners. These prepared refiners were subjected to microstructural studies by XRD and SEM/EDX. Characterization studies suggest that temperature of 800 °C has revealed the hexagonal morphologies of aluminium boride intermetallic particles with wide size ranges and more uniform distribution which are confirmed by the EDX analysis. However, other reaction temperatures (900 °C and 1000 °C) have resulted in formation of elongated and agglomerated morphologies of aluminium boride intermetallic particles. Aluminium borides present in various Al–4B refiners enhance in size with enhancement in processing time (from 45 to 75 min) and processing temperature (from 800 to 1000 °C). Among all the reaction temperatures and times studied, high volumes of the aluminium borides (smaller than 10 μm) were observed at 800 °C-60 min Further, by adding fixed amount of 0.01%B prepared master alloys were tested for refining performance on Al–7Si alloy. Results of grain refinement suggest that addition of 0.01% of B using Al–4B refiners produced at 800 °C-60 min have shown better refinement of α-Al at both shorter (2 min) and extended (120 min) holding periods. Minimum and constant DAS (62 μm) is achieved when refined with Al–4B refiner prepared at 800 °C-60 min