The Effect of Refractory Elements on Microstructure and Mechanical Properties of Ni₃(Si,Ti) Intermetallic Alloys

Abstract:

Microstructure, mechanical properties and cold workability of quaternary Ni3(Si,Ti) intermetallic alloys with L12 structure, which were alloyed with two atomic percent of a refractory element X (X: Hf, Ta and W), were investigated. The Ta-added Ni3(Si,Ti) alloy showed an L12 single phase microstructure, while the microstructure of the Hf-added alloy was comprised of Ni5Hf and/or Ni3Hf intermetallic dispersions in the L12 matrix, and that of the W-added alloy consisted of fcc Ni solid solution phase within the L12 grain. In the homogenized condition, hardness increased in the order of the Hf-added, the Ta-added and the W-added alloys. The hardenings of the Hf-added and the Ta-added alloys were attributed to second-phase dispersion hardening and distinctive solid solution hardening, respectively. Among these alloys, only the W-added alloy was successfully cold-rolled to thin sheet with a thickness of 200 m. It was found that both room-temperature and high-temperature tensile strength of the W-added alloy sheet was enhanced compared with that of the unalloyed Ni3(Si,Ti) sheet. Also, high-temperature tensile ductility was significantly improved in the W-added alloy sheet, by suppressing the propensity of brittle intergranular fracture.

• Periodical: Materials Science Forum (Volumes 654-656)
• Pages: 472-475
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.654-656.472
• Online since: June 2010
• Authors: Akiko Kai, Daiki Imajo, Yasuyuki Kaneno, Takayuki Takasugi
• Keywords: Cold Rolling, Mechanical Property, Microstructure, Ni₃(Si,Ti), Ordered Intermetallic Alloy, Refractory Metal

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