Investigation of the vacuum hot pressing process on the mechanical properties, microstructures and material characteristics of Ni–35Mo–15Cr alloys

ABSTRACT

This study fabricated Ni–35Mo–15Cr alloys by the vacuum hot pressing technique. The experiments utilised various hot pressing temperatures (1050°C, 1100°C, 1150°C, and 1200°C) and pressures (20, 35, and 50 MPa) to determine the optimal parameters for Ni–35Mo–15Cr alloys. The experimental result showed that the optimal hot pressing parameters of this alloy were 1150°C at 35 MPa for 1 h. Among them, the sintering density reached 8.92 g·cm⁻³, and the hardness and TRS increased to 77.1 HRA and 1218.2 MPa, respectively; while, the electrical conductivity was 7.08 × 10³ S cm⁻¹ and the polarisation resistance was 294.65 Ω·cm². Furthermore, the TEM observation identified the HCP structures of the Mo₂C that precipitated in the Ni–35Mo–15Cr alloys, and the [02$\overline{2}$1] and [01$\overline{1}$2] crystal axis of Mo₂C can be found. Overall, the properties of Ni–35Mo–15Cr alloys were effectively improved through the hot pressing process.

KEYWORDS:

• Ni–35Mo–15Cr
• hot pressing
• hardness
• TRS
• electrical conductivity
• TEM

Acknowledgements

This research is supported by the ASSAB STEELS TAIWAN CO., LTD. The authors would like to express their appreciation for Dr. Harvard Chen, Michael Liao and Mr. Meng-Yu Liu.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Shih-Hsien Chang

Shih-Hsien Chang: Writing and editing. 1993–1995, M.S. in Materials Science and Engineering, National Cheng Kung University; 2001–2006, Ph.D. in Materials Science and Engineering, National Cheng Kung University; Feb. 2015–present, Professor, Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taiwan, ROC.

Yi-Chang Hsiao

Yi-Chang Hsiao: Data curation and experimental preparation. 2018–2020, M.S. in Institute of Materials Science and Engineering, National Taipei University of Technology, Taiwan, ROC.

Kuo-Tsung Huang

Kuo-Tsung Huang: Review and editing. 2001–2007, Ph.D. in Materials Science and Engineering, National Cheng Kung University; Aug. 2001–present, Lecturer and Principal’s Office Chief Secretary, Department of Auto-Mechanics, National Kangshan Agricultural Industrial Senior High School, Kaohsiung, Taiwan, ROC.