Near-Surface and Bulk Dissolution Behavior of γ′ Precipitates in Nickel-Based VDM® Alloy 780 Studied with In-Situ Lab-Source and Synchrotron X-ray Diffraction

The dissolution of nano-sized Ni3Al-based γ′ precipitates was investigated in the newly developed polycrystalline nickel-based VDM® Alloy 780 at surface and bulk region with in-situ lab-source synchrotron X-ray diffraction. These studies are important obtaining a deeper understanding strengthening mechanism responsible for stability long service lives such superalloys. We found that behavior phase is very similar region, but small deviations were detected. starts around 800 °C no temperatures exceeding 970 °C. As result, elements Al Nb, which bound phase, dissolved into γ matrix strongly increased lattice parameter, as their atomic size larger than γ-forming Ni, Co, Cr. However, this effect suppressed area. A second detected same temperature range XRD measurements. formed γ-2 had smaller parameter initial matrix. propose result high-temperature oxidation, consumes, among other elements, Nb and, therefore, leads to parameter.