Grain Refinement of Aluminium Alloys by Inoculation

Abstract

A review is given of the studies of aluminium inoculation undertaken within the EU Network “Microstructural Engineering by Solidification Processing” (MEBSP). A wide range of studies of industrial practice of grain refining and of the fundamental mechanisms of nucleation and growth have contributed to improved understanding. Particular advances have been made in understanding the relative performance of different grain refiners.

Crystallographic study of grain refinement of Al by Nb addition

“…This not only improves the casting soundness and mechanical properties but also increases the formability during subsequent forming processes and ensures consistently better performance of the final products (McCartney, 1989;Murty et al, 2002;Quested, 2004). During the past six decades, extensive research has been carried out to clarify the mechanism underlying grain refinement, and a number of theories/models have been proposed (Cibula, 1949(Cibula, , 1951Crossley & Mondolfo, 1951;Marcantonio & Mondolfo, 1971;Backerud et al, 1991;Jones & Pearson, 1976;Easton & StJohn, 1999a,b;Johnsson et al, 1993;StJohn et al, 2011;Greer et al, 2003;Quested & Greer, 2004). It is now well recognized that two essential components, i.e.…”

Influence of filler wire composition on weld microstructures of a 444 ferritic stainless steel grade

“…The inoculant effect of Ti has been extensively studied by Greer et al (2003) for aluminium alloys. In these alloys, Ti formed refractory compounds on the molten metal that acted as heterogeneous nucleation sites for the grains solidification.…”

Modeling and characterization of grain structures and defects in solidification

“…Production of new grains by dendrite fragmentation should consider remelting, for which there are limited studies only [70]. Heterogeneous nucleation on foreign particles such as Al on TiB 2 or TiC particles has been shown to be athermal and thus does not follow standard theories, at least at small undercooling [11]. Finally, it has been shown recently that homogeneous nucleation in the liquid might depend on the short range order of atoms in the liquid, itself influenced by minute additions of solute elements [71].…”

“…Assuming athermal nucleation on inoculant particles such as TiC characterized by a size distribution [11], the evolution of each class of inoculant particles can be tracked. These inoculant particles are assumed to be transported with the velocity of the liquid until they become active at their corresponding undercooling and become grains.…”