Pressure-driven dynamic sintering mechanism and fracture failure mode in bimetallic surface coating composite interfacial nanoparticle

WS Lv and JW Lv and SH Wei and JX Liu and C Chen and Y Kang, POWDER TECHNOLOGY, 466, 121476 (2025).

DOI: 10.1016/j.powtec.2025.121476

Understanding the underlying sintering diffusion mechanism and mechanical failure modes of bimetallic surface coating nanoparticles under pressure-driven sintering can promote the synthesis and application of die-attach materials. In this paper, we innovatively proposed a continuous molecular dynamics (MD) method to reveal the fusion mechanism and surface mechanical response of Cu@Ag bimetallic surface coating composite nanoparticles under pressure-assisted sintering. The results indicate that the thickness of the coating and the sintering temperature have a synergistic regulatory effect on the sintering kinetics and structural evolution. There is a critical threshold for the thickness of the coating, which can significantly regulate the topological evolution of diffusion paths through the formation of stacking faults and dislocations. The sintering temperature affects the competitive mechanism between dislocation proliferation and slip by adjusting the diffusion activation energy. The triple coupling mechanism of "diffusion-interface-deformation" in bimetallic composite materials was first elucidated through uniaxial tensile simulation. Changing the thickness of coating can regulate the diffusion path and interface stress state, combined with the activation effect of sintering temperature on the deformation mechanism, jointly inducing the evolution of the material from brittle fracture to ductile fracture and then to adhesive fracture. This study provides new theoretical basis for design of coating nanoparticle materials, especially the discovery of critical thickness effects and coupling mechanisms, advancing high performance die-attach materials.

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