Microsegregation in Al–4.5Cu wt.% alloy: experimental investigation and numerical modeling

摘要: Abstract Microsegregation in Al–4.5 wt.%Cu alloy was investigated experimentally using directional solidification and electron probe microanalysis (EPMA). The degrees of dendrite tip undercooling were measured for growth rates from 0.0038 to 0.2 mm s−1 with a temperature gradient 50°C cm−1 at the liquid–solid interfaces. A modified Scheil model incorporating back diffusion, arm coarsening used calculate microsegregation. partition coefficients obtained thermodynamic models solid liquid phases cooling curves as inputs carry out microsegregation calculation. While calculated results deviate significantly experimental data, those are much better. Out three geometrical models, i.e. plate, sphere cylinder, approximate shapes dendrites, is best. However, spherical near accord data small fractions solids cylinder better large solids. Two different descriptions Al–Cu system demonstrate importance reliable phase diagram studying degree