Abstract
The lattice parameters and misfit of the γ and γ′ phases in a series of model quaternary Ni-based superalloys with and without Mo additions have been determined using neutron diffraction between room temperature and 700 °C. Despite the fact that Mo is typically expected to partition almost exclusively to the γ phase and thereby increase the lattice parameter of that phase alone, the lattice parameters of both the γ and γ′ phases were observed to increase with Mo addition. Nevertheless, the effect on the γ lattice parameter was more pronounced, leading to an overall decrease in the lattice misfit with increasing Mo content. Alloys with the lowest Mo content were found to be positively misfitting, whilst additions of 5 at.% Mo produced a negative lattice misfit. A general decrease in the lattice misfit with increasing temperature was also observed.
Highlights
Ni-based superalloys derive their exceptional high temperature strength from the formation of ordered, L12 (Strukturbericht notation) γ0 precipitates embedded in a disordered, A1 γ matrix
Data were acquired between room temperature and 700 ◦ C to deduce the temperature dependence, covering the range of conditions typically encountered in service
It was found that increasing bulk Mo content and increasing temperature led to larger lattice parameters of both the γ and γ0 phases, even though Mo is expected to partition almost exclusively to the matrix phase
Summary
Ni-based superalloys derive their exceptional high temperature strength from the formation of ordered, L12 (Strukturbericht notation) γ0 precipitates embedded in a disordered, A1 γ matrix. Due to their similar crystal structures and lattice parameters, the L12 precipitates are coherent with the A1 matrix and impart strength through a number of mechanisms, such as order and coherency strengthening [1]. A full understanding of the link between bulk alloy composition, phase composition and lattice misfit, and how they vary between ambient and service temperature is, important for the effective optimisation of alloy properties such as yield strength. Data were acquired between room temperature and 700 ◦ C to deduce the temperature dependence, covering the range of conditions typically encountered in service
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
