摘要
The microstructural evolution process of fined-grained ZA27 alloy during partial remelting has been investigated. The relationship between the as-cast and semi-solid microstructures has been discussed in particular. The results indicate that a semi-solid microstructure with small and spheroidal primary particles can be obtained when the ZA27 alloy is partially remelted. The microstructural evolution can be divided into four stages, the initial coarsening of the dendrites due to coalescence of dendrite arms, structural separation resulted from the melting of residual interdendritic eutectic, spheroidization due to the partial melting of solid particles and final coarsening attributed to the coalescence and Ostwald ripening. An equiaxed dendrite in the as-cast microstructure may evolve into one spheroidal particle in the semi-solid microsturucture after being partially remelted. The more equiaxed the dendrites in an as-cast microstructure are, the more spheroidal the solid particles in the semi-solid microstructure will be. Finer primary particles could be obtained if the alloy with finer as-cast microstructure was partially remelted. However, due to the coalescence effect, their sizes cannot be reduced further if the refined as-cast microstructure reached a certain extent.
The microstructural evolution process of fined-grained ZA27 alloy during partial remelting has been investigated. The relationship between the as-cast and semi-solid microstructures has been discussed in particular. The results indicate that a semi-solid microstructure with small and spheroidal primary particles can be obtained when the ZA27 alloy is partially remelted. The microstructural evolution can be divided into four stages, the initial coarsening of the dendrites due to coalescence of dendrite arms, structural separation resulted from the melting of residual interdendritic eutectic, spheroidization due to the partial melting of solid particles and final coarsening attributed to the coalescence and Ostwald ripening. An equiaxed dendrite in the as-cast microstructure may evolve into one spheroidal particle in the semi-solid microsturucture after being partially remelted. The more equiaxed the dendrites in an as-cast microstructure are, the more spheroidal the solid particles in the semi-solid microstructure will be. Finer primary particles could be obtained if the alloy with finer as-cast microstructure was partially remelted. However, due to the coalescence effect, their sizes cannot be reduced further if the refined as-cast microstructure reached a certain extent.
基金
supported by the Development Program for Outstanding Young Teachers and Doctor Foundation of Lanzhou University of Technology
