Influence of SiC particles size and undercooling on AZ91 based composite heterogeneous nucleation model parameters

Abstract

The aim of this paper was to determine fitting parameters in grain density of the magnesium primary phase function in AZ91/SiC composite heterogeneous nucleation model. Nucleation models have parameters, which exact values are usually not known and sometimes even their physical meaning is under discussion. Those parameters can be obtained after statistical analyze of the experimental data. Specimens of fourteen different composites were prepared. The matrix of the composite was AZ91 and the reinforcement was SiC particles. The specimens differs in SiC particles size (10 μm, 40 μm, 76 μm) and content (0 wt.%, 0.1 wt.%, 0.5 wt.%, 2 wt.%, 3.5 wt.%). They were taken from the region near to the thermocouple, to analyze the undercooling for different composites and its influence on the grain size. The specimens were polished and etched. The mean grain size for each specimen was measured. Specific undercooling for each composite was found from characteristic points on cooling rate curve. Microstructure and thermal analyze gave set of values that connect SiC particles content, their size and alloy undercooling with grain size. Those values were used to approximate nucleation model adjustment parameters. Obtained model can be very useful in modelling composites microstructure.

Citation

Zak, P., Lelito, J., Suchy, J., Krajewski, W., Haberl, K. and Schumacher, P. (2011), "Influence of SiC particles size and undercooling on AZ91 based composite heterogeneous nucleation model parameters", World Journal of Engineering, Vol. 8 No. 3, pp. 277-282. https://doi.org/10.1260/1708-5284.8.3.277