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Catalytic efficiency of oxide particles on heterogeneous nucleation in aluminium alloys with miscibility gap
Ivan Kaban, Markus Köhler, Walter Hoyer and Lorenz Ratke

It is shown that ZrO2 nanoparticles essentially stimulate the heterogeneous nucleation of droplets from the minority phase in Al-Pb monotectic alloys, which results in a significant increase of the number of Pb particles and in a decrease of their size upon solidification. This is related to the contact angle between coexisting liquid phases and ZrO2 ceramic, which is 20–30 degrees in the Al35Pb65 alloy and 35–40 degrees in the Al29.4In70.6 alloy. In the Al34.5Bi65.5 alloy at 670ºC, the contact angle at the (l-l) interface and ZrO2 ceramics shows a hysteresis between 37º and 115º. The contact angle between coexisting liquid phases and Al2O3 ceramic is close to zero in the Al34.5Bi65.5 alloy.

Keywords: aluminium alloys; miscibility gap; wetting; heterogeneous nucleation; inoculants.

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