Indexed by: Journal paper

Journal: Journal of Alloys and Compounds

Included Journals: SCI

Discipline: Engineering

First-Level Discipline: Material Science and Engineering

Document Type: J

Page Number: 164668

Key Words: Nickel-based superalloy；hot isostatic pressing；PPBs；microstructure；tensile property

Date of Publication: 2022-03-21

Impact Factor: 5.316

Abstract: A third-generation powder metallurgy nickel-based superalloy (WZ-A3) was prepared by hot isostatic pressing (HIP) at 1100 oC, 1150 oC, 1200 oC, and 1250 oC, respectively. The characteristics of grains, precipitates, and elemental distribution revealed its microstructural development. The samples prepared at a sub-solvus temperature (1100 oC) consisted of fine recrystallized grains and dendritic structures. However, the microstructure became a completely recrystallized structure when the HIP temperature reached or exceeded 1150 oC. The average grain size increased from 4.0 μm (1100 oC) to 53.1 μm (1250 oC) due to the promoted recrystallization and atom diffusion rate. Prior particle boundaries (PPBs) with continuously distributed precipitates were identified as a mixture of (Nb, Ti)C carbides and Hf0.5Zr0.5O2 oxides. By increasing the HIP temperature from 1100 oC to 1200 oC, the PPBs were reduced but not eliminated. As a result, samples prepared at 1200 oC experienced interparticle debonding with relatively high strengths, and the ultimate tensile strength values were 1388.7 MPa and 1228.3 MPa at room temperature (RT) and 700 oC, respectively. When the HIP temperature was 1250 oC, the presence of coarse grains, large carbides, as well as eutectic structures formed at the junction of grain boundaries caused dramatic drops of tensile strengths and brittle fractures. These results emphasized the importance of parameter optimization for controlling the microstructure and mechanical properties during the HIPing process.

Links to published journals: https://doi.org/10.1016/j.jallcom.2022.164668