Author/Authors :
Kolbe، نويسنده , , M. and Liu، نويسنده , , X.R. and Volkmann، نويسنده , , T. and Rِstel، نويسنده , , R. and Galenko، نويسنده , , P.K. and Eggeler، نويسنده , , G. and Wei، نويسنده , , B. and Herlach، نويسنده , , D.M.، نويسنده ,
Abstract :
Many technical materials contain inclusions or precipitates, mainly for improving their mechanical properties, but which may also arise from processing. A rather new development is the production of particle-strengthened material directly from the melt. The distribution of the particles in the solidified melt is determined by the interaction of the particles with the advancing solidification front: (i) The particles are pushed by the solidification front and are entrapped in the last solidifying part of the melt. (ii) In the case of dendritic solidification, particles are trapped in the interdendritic region. (iii) The solidification front engulfs the particles and they are embedded homogeneously into the alloy. An important experimental parameter, which determines the governing mechanism of the interaction, is the velocity of the solidification front. It can be measured and varied widely by undercooling the alloys containerlessly in an electromagnetic levitation facility. Due to the high undercooling level the microstructure is frozen in instantaneously by rapid solidification and is accessible for post-mortem metallographic investigation. In the present paper first solidification experiments are reported for the systems Ni+Ta2O5, Cu+Ta2O5 and Cu50Ni50+Ta2O5.
