Vacuum diffusion bonding of TC4 titanium alloy to 316L stainless steel with AlCoCrCuNi2 high-entropy alloy interlayer

A newly designed AlCoCrCuNi2 high-entropy alloy (HEA) interlayer was used for vacuum diffusion bonding of TC4 titanium alloy (TC4) to 316L stainless steel (316L). The sluggish diffusion effect suppressed the formation and growth of intermetallic compounds (IMCs). The effect of bonding temperature on the microstructure evaluation, the elemental diffusion behavior and mechanical property of the joint was investigated. The HEA interlayer and 316L substrate present a reliable metallurgical combination, and solid solution zone was formed at the HEA/316L interfacial diffusion zone. The typical microstructure of the TC4/HEA diffusion zone was composed of alpha + beta-Ti/Ti2Ni/Ti(Co, Ni)/Al(Co, Ni)(2)Ti+Cr-rich phase/discontinuous precipitation zone/HEA interlayer. The diffusion zone near the B2 phase presented a lower growth activation energy than that near the FCC phase on the 316L side. As the bonding temperature increased from 860 degrees C to 1010 degrees C, the interface of TC4/Ti2Ni changed from straight to serrated structure, which prevented the crack propagation and enhanced the mechanical properties of the joint. The maximum shear strength of 214 MPa was obtained at the bonding temperature of 1010 degrees C. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the vacuum diffusion bonding of TC4 titanium alloy to 316L stainless steel using a newly designed high-entropy alloy interlayer. It was found that increasing the bonding temperature enhanced the mechanical properties of the joint significantly.