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DOE OSTI2020

Materials Data on Cr5B3 by Materials Project

Cr5B3 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Cr sites. In the first Cr site, Cr is bonded in a 5-coordinate geometry to five B atoms. There are a spread of Cr–B bond distances ranging from 2.16–2.27 Å. In the second Cr site, Cr is bonded in a 6-coordinate geometry to six B atoms. There are four shorter (2.18 Å) and two longer (2.49 Å) Cr–B bond lengths. There are two inequivalent B sites. In the first B site, B is bonded in a 10-coordinate geometry to ten Cr atoms. In the second B site, B is bonded in a 9-coordinate geometry to eight Cr and one B atom. The B–B bond length is 1.81 Å.

36 MATERIALS SCIENCE↗

NASA NTRS1992

Microstructural observations in rapidly-solidified and heat-treated Ni3Al-Cr alloys

The microstructural development following heat treatments of several rapidly-solidified Ni3Al-Cr and Ni3Al-Cr-B alloys is presented. Depending on composition, the as-solidified samples were either 100 percent gamma-prime phase - in the form of fine antiphase domains (APD) - or a mixture of gamma-prime (APDs) and beta phases. Upon annealing, the as-solidified microstructures transform to either APD-free gamma-prime or mixtures of gamma and gamma-prime phases. For those compositions where the quenched microstructures were 100 percent gamma-prime it was observed that APD coarsening followed conventional grain-growth kinetics, but when gamma phase precipitated on the APD boundaries the rate constant changed abruptly while the time exponent remained unaffected. It was also found that alloys containing critical amounts of chromium and boron are susceptible to precipitation of the boride Cr5B3.

Carro, G.↗