Promoting the sintering densification and mechanical properties of gas-atomized high-entropy alloy powder by adding boron
| Autor: | Chi-San Chen, Chia-Yu Lin, Yu-Cheng Fu, Ming-Wei Wu, Yi-Ling Lin |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Mechanical Engineering Alloy Metallurgy Sintering engineering.material Condensed Matter Physics Microstructure chemistry.chemical_compound Compressive strength Differential scanning calorimetry chemistry Mechanics of Materials Phase (matter) Boride Powder metallurgy engineering General Materials Science |
| Zdroj: | Materials Characterization. 179:111370 |
| ISSN: | 1044-5803 |
| DOI: | 10.1016/j.matchar.2021.111370 |
| Popis: | Powder metallurgy (PM) with pressure-assisted sintering is a versatile process for producing high-entropy alloys (HEAs) with a fine grain size and high strength. Unfortunately, HEA powders are extremely difficult to sinter with a general press-and-sinter PM process due to the sluggish diffusion effect in HEAs. One economical means to effectively densify the PM materials is liquid phase sintering (LPS). According to the phase diagrams, boron (B) is a feasible element for facilitating LPS of an AlCoCrFeMoNi powder because B can react with Co, Cr, Fe, Mo, and Ni to generate a low-temperature liquid phase. The objective of this study was thus to conduct the first investigation of the influences of 0.8 wt% B on the sinterability, microstructure, and mechanical properties of the AlCoCrFeMoNi HEA powder. The results showed that after 1200 °C sintering, the densification behaviors of both the AlCoCrFeMoNi and AlCoCrFeMoNi+0.8B alloys were undesirable. However, adding 0.8 wt% B to AlCoCrFeMoNi and sintering at 1220 °C significantly increased the densification and reduced the porosity from 11 vol% to 1 vol%. The onset temperature for liquid generation was identified as 1205 °C by differential scanning calorimetry curve. The microstructure of the AlCoCrFeMoNi alloy sintered at 1220 °C was face-centered cubic and sigma phases. The 0.8 wt% B additive led to the generation of Mo2FeB2 boride at the expense of sigma phase. Furthermore, adding 0.8 wt% B to the AlCoCrFeMoNi alloy sufficiently improved the yield strength by 42%, ultimate compressive strength by 66%, and fracture strain by 92%, due to the LPS effect. The AlCoCrFeMoNi powder was successfully sintered by adding B to facilitate LPS. In the future, this alloy design can be also applied to the other HEA powders that contain principal elements that react with B to form a low-temperature liquid. |
| Databáze: | OpenAIRE |
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