Measurement of grain bridging in some Al-Cu and Al-Sn alloys

A quantitative investigation of interdendritic bridging in some Al-Cu and Al-Sn alloys is presented. The experimental measurement methods and bridging fractions at different eutectic liquid fractions are given. The different bridging fractions in Al-Cu and Al-Sn of different compositions- have been found, and the effect of grain refinement on the bridging between the grains is analysed. The measurement is based on metallographic investigation of samples that have been quenched just above the eutectic temperature. Electron microprobe analyses across the bridges have been done and the diffusion of Cu in Al has been calculated in order to rule out alternative interpretations of experimental investigations. Finally, the possibilities of incorporating the experimental results into hot tearing models are discussed. (C) 2003 W. S. Maney Son Ltd.