Ultrafast bimetallic interface reinforcement in additively manufactured multi-material via electropulsing

The bimetallic interface in additively manufactured multi-material was subjected to intense thermal cycling, and thus forming sizable heat affected zone and drastic mutation of chemical component, which led to weak metallurgical bonding. In this investigation, the pulsed current (1255Hz; 64 μs; 35.4V; 191A; 1000 ℃; 20min) was used to rapidly broaden the compositional mutation zone from 16 μm to 45 μm, and the heat affected zone was completely eliminated. However, the roles of equivalent heat treatment (1000 ℃; 20min) were opposite with the pulsed one. The width of compositional mutation zone became narrower and the morphology heat affected zone did not change after equivalent heat treatment. Furthermore, the hot compression experiment proved the better bimetallic interface quality of pulsed sample. The rapid regulation of microstructure and composition gradient is caused by increasing interfacial diffusion flux and the promotion of electron wind force to the solute atom.