Abstract
Interfacial stability conditions of Al-Cu alloys were investigated under gravity force and centrifugal forces of 2G and 5G. Specimens were unidirectionally solidified and quenched during solidification. Stability conditions under the acceleration of 1G, 2G and 5G were determined. The result in 1G experiments agrees with those in other works. On the contrary, planer interfaces under additional acceleration are more unstable than that in 1G experiments under the same conditions. The equilibrium partition coefficient, k, and the diffusion coefficient of copper in the melt D, were determined by XMA analysis.
Determined values for 1G, 2G and 5G experiments are 0.163, 0.162 and 0.162, and 4.76×10−9, 4.53×10−9 and 4.58×10−9 m/s, respectively. Decrease of diffusion coefficient is presumably due to gravity segregation and pressure enlarged by additional acceleration. The extension of unstable regions in 2G and 5G experiments is attributed to this decrease of the diffusion coefficient and some micro convection which may be enlarged by additional acceleration.
