Abstract
Solidification microstructure and growth interface morphology of directionally solidified Ni–31Al–32Cr–6Mo(at.%) hypereutectic alloy were studied. The experiments were carried out at higher temperature gradient of about 250 K cm −1 with different withdrawal rates of 4–500 μm s −1. When the withdrawal rate was less than 50 μm s −1, the primary Cr(Mo) dendrites were gradually eliminated through competitive growth between the primary phase and the eutectic phase. When the withdrawal rate exceeded 100 μm s −1, no primary phase formed, eutectic phase grew directly. Fully eutectic microstructures with lamellar morphology were observed at all withdrawal rates. With increasing withdrawal rate V, the growth interface changed from planar to cellular and then dendritic, the solidification microstructure also transformed from planar eutectic to two-phase cellular eutectic and dendritic eutectic. The microstructure was refined and the eutectic interlamellar spacing λ decreased according to the relationship of λ = 4.82 V −0.42. Compared to the alloy at eutectic composition, the volume fraction of Cr(Mo) strengthening phase was increased obviously.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.