Evaluation of particle size and particle shape distributions in Al-Al 3Ni FGMs fabricated by a centrifugal in-situ method

Abstract

This paper reports on the variation of particle size, particle shape and volume fraction distributions in Al-Al3Ni functionally graded materials (FGMs) fabricated by a centrifugal in-situ method. Eight specimens of Al-Al3Ni FGM were systematically selected for the experimental analysis. The microstructures of Al3Ni primary crystal particles were observed and then gradients of volume fraction of Al3Ni particles towards centrifugal force direction were measured. A detailed evaluation of particle size was done considering the area-equivalent diameter from cross-sectional area of each Al3Ni particle. Moreover, particle shape distributions were also conducted using functions concerning with both fractal dimension and circularity of particles. It is revealed that both particle size and particle shape of Al3Ni had graded distributions as well as volume fraction distributions within the FGMs. Those results were explained considering the effect of applied G number, Ni content in Al-Ni master alloy, cooling rate and stirring of melt.