Microstructure Evolution and Solid Solubility of Nickel in Al-10wtNi Hypereutectic Alloy Solidified under Steady Magnetic Fields

摘要

The microstructures and solid solubility of Al-10wt% hypereutectic alloy solidified under steady magnetic fields which intensity is from 0 Tesla to 0.25 Tesla are investigated. The normal microstructure of Al-10wt%Ni hypereutectic alloy should be compounded of the primary dendrite Al_3Ni and eutectic. But solidified under 0.178 Tesla, the microstructure has been transformed into eutectic. The quantitive metallographical analysis shows primary dendrites Al_3Ni are suppressed, and the amount of Al_3Ni composed of the primary den-drites and Al_3Ni of eutectic also decreases while the alloy solidified under steady magnetic fields. The solid solubility of nickel in aluminum increases dramatically, and then the lattice parameter of aluminum will decrease because the atomic radius of aluminum is larger than that of nickel, those phenomena can be explained by the effect of the magnetic field on Gibbs free energy. Investigating this subject contributes to understanding the influences of steady magnetic field on solidification.