Affiliation:
1. State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an Shaanxi 710072 P. R. China
2. School of Materials Science and Engineering Northwestern Polytechnical University Xi'an Shaanxi 710072 P. R. China
3. Research & Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen Guangdong 518063 P. R. China
Abstract
By regulating Inconel718‐xRene88DT (x = 0–100%) alloy powder, microstructure evolution and microsegregation of as‐deposited samples fabricated by direct energy deposition (DED) are investigated. The novelty of this approach lies in the systematic regulation of the alloy composition to study its impact on microstructure and microsegregation, which is an important prerequisite to improving the performance of DED superalloys. It is found that the as‐deposited microstructure mainly consists of predominant γ columnar dendrites directionally growing along the deposition direction. With the increase of Rene88DT proportion, thelayered structure tends to be more obvious, and the amount and size of γ′ phase increases. The content of the Laves phase is in decline. As a result of the microsegregation, the needlelike δ (Ni3Nb) and lath‐shaped η (Ni3Ti) precipitate in the interdendritic regions when the proportion of Rene88DT is above 60%. The various microstructures, microsegregation, and their correlations at different proportions of Rene88DT DED samples are discussed. The relationship between composition and microstructure evolution is investigated based on the alloying mechanism, which can guide alloy design and process optimization for enhanced properties in AM‐built Ni‐based superalloys.
Funder
National Natural Science Foundation of China