Dynamics responses of the in situ magnetochemistry reaction for Al-Zr(CO3)2 system

The dynamics formation mechanisms of the Al2O3 and Al3Zr reinforcement phases fabricated from Al-Zr(CO3)2 system via magnetochemistry in situ reaction at 1173 K are investigated by XRD, SEM analysis and rapid water-quenching methods. The results show that in the primary stage of the in situ reactions, the melt aluminum begins to infiltrate and reacts with ZrO2, which comes from the decomposition of Zr(CO3)2 and is present in polygonal shape, the resultant particles are rapidly diffused out of the reaction layers. With the reaction processing, the melting temperature is increased and the metallurgy microzones with high temperature are created in the reaction layers. When the differences of temperature and thermal stress between the reaction and un-reaction layers are great enough, the reactant particles burst. These promote the diffusion of the resultant particles and increase the contact areas among the reactants. In the final stage, when the reaction time is 20 min, the in situ nanoparticles are formed and diffused uniformly in the aluminum matrix. The applications of the impulse magnetic field lead to the acceleration of in situ chemical reactions and the strong vibrations in the aluminum melt. These contribute to the small sizes, great amounts and much more uniform distributions of the in situ particles than those of zero magnetic field. The possible dynamics formation mechanism is as follows: reaction-bursting-diffusion.