Nickel interlayer-based approach for enhancing the creep and microstructural properties of TIG-welded AA2219 aluminum alloy joints

Abstract

This study investigates the influence of a nickel interlayer on the microstructure, mechanical properties, and creep performance of Tungsten Inert Gas (TIG)-welded AA2219 aluminum alloy, widely used in aerospace structures. A novel welding approach was employed by inserting 99.9% pure nickel foil between solution-treated AA2219 plates to enhance joint integrity. Optimized TIG welding trials were conducted under both single-pass and double-pass weld conditions, followed by comprehensive microstructural characterization, Vicker’s microhardness measurements, and thermo-static creep testing at 300°C under varying stress levels. The nickel interlayer promoted the formation of intermetallic compounds, including Al₂Cu and Al₂Ni, which refined the weld-zone grains and improved mechanical performance. The weld nugget exhibited a 25.18% increase in microhardness (94 HV) compared to the base material (70 HV). In creep testing, double-pass welds sustained 70 MPa with 2.71 mm elongation, representing a ∼20-fold improvement over single-pass welds. The findings demonstrate that nickel interlayers enhance weld texture, reduce defects, and improve directional strength, offering promising benefits for high-stress aerospace applications.

Graphical Abstract