Influence of a strong static magnetic field on the discontinuous precipitation reaction in Mg–9Al–1Zn alloy

Supersaturated Mg–9Al–1Zn (AZ91) specimens were annealed at 220 °C for different time up to 24 h with and without a 10 T static magnetic field. Quantitative metallurgraphy indicated that the macroscopic kinetics of the discontinuous precipitation reaction became slow under the magnetic field, and both the nucleation rate and the mean growth rate of discontinuous precipitation nodules decreased. The volume percentage of discontinuous precipitation finally transformed has also decreased under the magnetic field. Such effects were supposed to result from the retarded solute diffusion under the field. β lamellae inside precipitation nodules were found to have a smaller interlamellar spacing and grow in a more regular manner under the field.