Impurities in Al–5Ti–1B grain refiner rod

AbstractTwo different Al–5Ti–1B (wt-%) grain refiner rods (Rod A – a 'poor' refiner and Rod B – a 'standard' refiner) were examined using induced coupled plasma – optical emission spectroscopy (ICP-OES), computed tomography (CT) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) spectroscopy. CT with its digital geometrical processing allowed 3D images of non-destructed sections of the rod to be analysed. Results for Rod A revealed the presence of several types of inclusions up to several mm in size. Qualitative micro-chemical analysis using an SEM with EDX indicated that the inclusions were Ti, K and/or F rich. This would thus imply that the particles observed were, undissolved Ti/Al-Ti compounds namely Al3Ti and/or Al3Ti(Si), and potassium and fluoride spent salts namely KF-AlF3 flux. These findings are indicative of an inefficient, non-optimal manufacturing process. An assessment of the grain refining efficacy of both the rods using the TP1 test showed the standard rod (...