Design of low mass density γ/γ� CoNi-based superalloys with promising high-temperature mechanical properties

Pandey, P and Mazumder, N and Singh, MP and Patil, C and Sharma, A and Makineni, SK and Banerjee, D and Chattopadhyay, K (2021) Design of low mass density γ/γ� CoNi-based superalloys with promising high-temperature mechanical properties. In: Physical Review Materials, 5 (9).

	PDF phy_rev_mat_05-09_2021.pdf - Published Version Restricted to Registered users only Download (3MB) | Request a copy
	PDF Supplemental_material.pdf - Published Supplemental Material Restricted to Registered users only Download (677kB) | Request a copy

Abstract

We report new compositions of CoNi-based superalloys that have low mass densities (7.84-8.20 g/cc), negative γ/γ� lattice misfit, and high γ� solvus temperature up to 1094 °C with promising high-temperature mechanical properties. The γ/γ� in the base Co-30Ni-10Al-5Cr alloy was stabilized with Nb and further developed by varying Ti and Cr. The γ� precipitates in these alloys are richer in Ni than the γ matrix phase, unlike for γ� in other CoNi-based superalloys. The atomic-scale compositional analysis indicates that the γ� has a stoichiometry of (Ni,Co)3(Al,Nb,Ti,Cr). In these alloys, the γ� microstructure is stable at 900 °C up to 1000 h. In an alloy with a γ� solvus of 1089 °C, the coarsening kinetics of γ� at 900 °C follows the Lifshitz-Slyozov-Wagner model with a rate constant of 6.6±0.7nm3/s, comparable with high-density Co-Al-W-based superalloys. The alloys also show an anomalous increase in strength, with temperature having a peak of 0.2 proof stress (PS) and specific PS (SPS) of �710 MPa and �91MPag-1cc, respectively, at 770 °C. The low density and high strength make this class of alloys a potential and cost-effective alternative to the other Co-based superalloys and comparable with Ni-based superalloys. ©2021 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review Materials
Publisher:	American Physical Society
Additional Information:	The copyright for this article belongs to American Physical Society
Keywords:	Aluminum alloys; Chromium alloys; Coarsening; Cost effectiveness; Density (specific gravity); High strength alloys; Nickel alloys; Rate constants; Superalloys, 0.2 Proof stress; Co-based superalloys; Coarsening kinetics; Compositional analysis; High temperature mechanical properties; Low density and high strengths; Ni-based superalloys; Solvus temperature, Cobalt alloys
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	03 Dec 2021 08:27
Last Modified:	03 Dec 2021 08:27
URI:	http://eprints.iisc.ac.in/id/eprint/70201

Actions (login required)

View Item