Application of dendrite fragmentation to fabricate the homogeneous dispersed structure in undercooled Cu–Co immiscible alloy

► Dendrite fragmentation was compared beyond and within the immiscible gap. ► Homogeneous dispersion structure can be obtained at certain undercooling. ► Solute variation was applied to explain fragmentation by remelting and break-up. ► Thermodynamic calculation was performed to support the experimental results. The dependence of microstructure on undercooling for Cu 50Co 50 immiscible alloy and the relations between dendrite fragmentation and liquid phase separation were studied by melt-fluxing in combination with cyclic superheating. It is shown that homogeneous dispersed structure can be obtained by dendrite fragmentation because of the increased solute content in primary dendrite, which is advantageous for strengthening dendrite remelting effect and thermal plateau time following recalescence. As for the sample after liquid separation, typical dual-layer structure forms, while dendrite fragmentation still exists and its extent, volume fraction are influenced by the solute contents of two immiscible layers. Quantitative thermodynamic calculation was further performed to support the experimental results.