Corrosion Screening of Preserved Wire-Laser DED MoNiCr Surfaces in FLiBe at 750 °C

A custom low-chromium MoNiCr alloy produced by wire-fed laser directed energy deposition (W-DED) was exposed to eutectic LiF–BeF2 (FLiBe) at 750 °C for 1000 h to assess corrosion of the retained deposition surface. A nominally 100 × 100 × 100 mm cube was divided into as-built (AB) and hot-isostatically pressed (HIP) portions. Two coupons were extracted from each of the X–Y, Z–X, and Z–Y surface layers of each portion, giving 12 coupons. Each coupon was fully immersed in a separate nominally equal salt charge within a graphite crucible enclosed in an individually sealed AISI 304 capsule. Characterization focused on the original W-DED face. Optical profilometry compared exposed coupons with adjacent unexposed reference regions. Cross-sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy assessed microstructure and near-surface chemistry. The topography measurements showed substantial spatial variability and did not establish a consistent dependence on orientation or material condition. Backscattered-electron images and semiquantitative elemental profiles indicated a shallow near-surface region associated with Cr depletion, without establishing a quantitative penetration depth or corrosion rate. The results provide descriptive screening observations for retained W-DED surfaces under the specific static exposure conditions. Unmeasured salt redox potential and impurity concentrations, together with the limited replication, constrain their use in material qualification.