Effect of ultrasonic peening treatment on microstructure and properties of CMT additive-manufactured Ti6Al4V/Al6.21Cu dissimilar alloys with Nb interlayer

The layer-by-layer ultrasonic peening treatment (UPT) was utilized to refine the coarse microstructure and decrease the pore number and size in the Al alloy of the Ti6Al4V/Al6.21Cu bimetallic structure with Nb interlayer manufactured by cold metal transfer additive manufacturing. After UPT, the pore in the deposited Al layer was compressed. Grains were compressed and refined significantly in the transition layer under the effect of UPT. The Nb interlayer still acted as the diffusion barrier and impeded the formation of harmful Ti-Al intermetallic compounds after UPT. The mean ultimate tensile strength of the bimetallic structure with Nb interlayer after UPT was 164.5 MPa, and increased by 36.1% compared to that of the bimetallic structure without UPT. The fracture occurred at brittle Al3Nb reaction layer for all samples.

Automated summary

Layer-by-layer ultrasonic peening treatment (UPT) can refine the microstructure and reduce the pore number in the Al alloy of bimetallic structures, increasing the ultimate tensile strength. The Nb interlayer still acts as a diffusion barrier after UPT, preventing the formation of harmful intermetallic compounds.