Yc. Lee et al., The effect of grain refinement and silicon content on grain formation in hypoeutectic Al-Si alloys, MAT SCI E A, 259(1), 1999, pp. 43-52
The effect of increasing the amount of added grain refiner on grain size an
d morphology has been investigated for a range of hypoeutectic Al-Si alloys
. The results show a transition in grain size at a silicon concentration of
about 3 wt% in unrefined alloys; the grain size decreasing with silicon co
ntent before the transition, and increasing beyond the transition point. A
change in morphology also occurs with increased silicon content. The additi
on of grain refiner leads to greater refinement for silicon contents below
the transition point than for those contents above the transition point, wh
ile the transition point seems to remain unchanged. The slope of the grain
size versus silicon content curve after the transition seems to be unaffect
ed by the degree of grain refinement. The results are related to the compet
itive processes of nucleation and constitutional effects during growth and
their impact on nucleation kinetics. (C) 1999 Elsevier Science S.A. All rig
hts reserved.