Additional Phases at High Boron Content in High-Temperature Co-Re-Cr Alloys

0493524 - ÚJF 2019 RIV CH eng J - Článek v odborném periodiku
Beran, Přemysl - Mukherji, D. - Strunz, Pavel - Gilles, R. - Karge, L. - Hofmann, M. - Hoelzel, M. - Rösler, J. - Farkas, G.
Additional Phases at High Boron Content in High-Temperature Co-Re-Cr Alloys.
Metals. Roč. 8, č. 8 (2018), č. článku 621. E-ISSN 2075-4701
Grant CEP: GA ČR GB14-36566G; GA MŠMT LM2015056
Institucionální podpora: RVO:61389005
Klíčová slova: high-temperature alloys * Co-Re-Cr-based alloys * phase transformation * neutron diffraction * in-situ studies * scanning electron microscopy (SEM)
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 2.259, rok: 2018

Boron largely increases the ductility of polycrystalline high-temperature Co-Re-Cr alloys. Therefore, the effect of boron addition on the alloy structural characteristics is of large importance for the stability of the alloy at operational temperatures. Along with the Co-solid solution matrix phase transformation from hcp to fcc structure, additional structural effects were observed in situ at very high temperatures (up to 1500 degrees C) using neutron diffraction (ND) in boron-containing Co-17Re-23Cr alloys. Increasing boron content up to 1000 wt. ppm lowers the temperature at which sublimation of Co and Cr from the matrix occurs. As a result, the composition of the matrix in the surface region is changed leading to the formation of a second and a third matrix hcp phases at high temperatures. The consideration on the lattice parameter dependence on composition was used to identify the new phases appearing at high temperatures. Energy-dispersive spectroscopy and ND results were used to estimate the amount of Co and Cr which sublimated from the surface region of the high-boron sample. In the sense of alloy development, the sublimation of Co and Cr is not critical as the temperature range where it is observed (>= 1430 degrees C) is significantly above the foreseen operation temperature of the alloys (1200 degrees C).
Trvalý link: http://hdl.handle.net/11104/0286878