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

This study investigates the high-temperature corrosion behavior of two nickel-based alloys (602CA and alloy 625) in molten Solar Salt (60% NaNO 3 / 40% KNO 3 ) 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 Al 2 O 3 layers in 602CA and NiCr 2 O 4 /NiFe 2 O 4 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 Al 2 O 3 layer compared to those of the alloy 625 and 602CA-HR (>5μm, 0.0009mm/y and >15μm, 0.0006mm/y, respectively). These findings establish 602CA-AM as a promising candidate for critical CSP components. • 602CA alloy processed by Hot-Rolling (HR) and Additive-manufacturing (AM) were compared to 625 in molten nitrates. • Alloy 602CA-AM demonstrated the best performance, with 50% thinner oxide scales (10 μm) and lower corrosion rates (0.0003 mm/y). • Distinct oxide layers were identified, with both 602CA-HR and 602CA-AM forming continuous Al 2 O 3 layers, while all alloys developed NiCr 2 O 4 /NiFe 2 O 4 spinels.