Microstructures and properties of in-situ formed core-shell (TaTiCr)B2 particles reinforced copper matrix composites prepared via casting

To avoid the macro-segregation and micro-agglomeration of reinforcements during the preparation of copper matrix composites via casting, redesigning the reinforcements to match the density with that of the matrix may effectively avoid macro-segregation. However, addressing micro-agglomeration remains a significant obstacle limiting broader application. In this work, the finer and more uniform (TaTiCr)₂B/Cu composites were successfully prepared through the design of core-shell (TaTiCr)B₂ ceramic particles. Furthermore, the formation and dispersion mechanisms of core-shell (TaTiCr)B₂ particles were elucidated. During the growth process of novel diboride particles, the Ta and Ti elements exhibit relatively high adsorption energy to facilitate the formation of homogeneous distribution of components, but their higher interfacial energies induce severe micro-agglomeration of (TaTi)B₂ particles. Conversely, the Cr element displays low adsorption energy, resulting in the formation of core-shell (TaCr)B₂ structure. However, the Cr element may significantly reduce the interfacial energy, causing the particles to tend to be dispersed. Ultimately, by co-selecting Ta, Ti and Cr elements, the high-strength and high-conductivity copper matrix composites reinforced with finer and more dispersed (TaTiCr)B₂ particles were prepared.