An investigation on physical and chemical refinement of aerospace aluminium alloys

Conventional grain refinement is performed through the addition of chemical refiners. However, this article proposes physical refinement as an alternative method for producing fine grain size. Two methods of physical refinement are examined and evaluated, namely Melt Conditioning by Advanced Shear Technology (MCAST) and the use of an Ultrasonic technique. The results were compared with the conventional method of grain refining. The outcomes indicate that the Ultrasonic technique can be used for grain refinement of alloys that cannot be chemically refined. Moreover, this technique seems to overcome other problems associated with the addition of grain refiners or the MCAST method.

► Physical grain refinement methods (ultrasonic, MCAST) applied.
► Comparison with chemical refinement.
► Physical refinement by cavitation more powerful than chemical.
► Ultrasonic technique most effective method among physical grain refinement techniques.