A high-temperature study of hot-rolled and additive-manufactured Ni-based alloys for CSP applications

Abstract

This study investigates the high-temperature corrosion behavior of two nickel-based alloys (602CA and alloy 625) in molten Solar Salt (60% NaNO3 / 40% KNO3) at 580 °C, comparing hot-rolled (HR) and Laser Power Bed Fusion (PBF-LB/M) processing routes with the target of comparing the conventional versus the Additive Manufacturing (AM) processes. Through integrated gravimetric analysis, SEM-EDS characterization, and XRD phase identification, it has been demonstrated how composition and manufacturing process govern corrosion resistance. The work addresses the role of protective oxide formation, including Al2O3 layers in 602CA and NiCr2O4/NiFe2O4 common to both alloys. Key results reveal that AM-processed 602CA exhibits superior performance, with 50% thinner oxide scale (10 μm), corrosion rates (0.0003 mm/y), and a denser and more continuous Al2O3 layer compared to those of the alloy 625 and 602CA-HR (>5 μm, 0.0009 mm/y and >15 μm, 0.0006 mm/y, respectively). These findings establish 602CA-AM as a promising candidate for critical CSP components.