Controlling the diffusion behavior in diffusion bonded reduced activation Cr0.8FeMn1.3Ni1.3 high entropy alloy/316SS joints through dislocations

Abstract

Diffusion bonding between Co-free Cr_0.8FeMn_1.3Ni_1.3 high entropy alloy (HEA) and 316 stainless steel (316SS) was systematically investigated, emphasizing the enhancement of interfacial atomic diffusion through dislocation-mediated diffusion pathways induced by cold rolling deformation. The dislocation density increased significantly from 8.31 × 10¹² m⁻² at 0 % deformation to 7.80 × 10¹³ m⁻² at 20 % deformation, resulting in a substantial reduction in the activation energy for diffusion from 80.5 kJ/mol to 47.2 kJ/mol, corresponding to a decrease of approximately 41 %. Concurrently, the diffusion coefficient of Fe from 316SS into the HEA notably increased from 9.35 × 10⁻¹⁵ m²/s to 2.15 × 10⁻¹⁴ m²/s, indicating significantly enhanced atomic transport. This enhanced diffusion facilitated more effective interfacial atomic mixing and continuous solid-solution formation across the joint interface. Consequently, the mechanical properties of the bonded joints improved, as evidenced by a 9 % increase in ultimate tensile strength (UTS), which is attributed to enhanced atomic intermixing and reduced local stress concentrations. The results demonstrate the effectiveness of dislocation engineering in optimizing atomic diffusion kinetics and mechanical performance in HEA/stainless steel diffusion bonded joints, offering a promising approach for enhancing joint reliability in nuclear structural applications.