Open AccessКристаллографические особенности структуры литых и закаленных сплавов кобальт--ниобий
Author(s) -
Ю.В. Хлебникова,
Л.Ю. Егорова,
Т.Р. Суаридзе,
Ю.Н. Акшенцев
Publication year - 2020
Publication title -
žurnal tehničeskoj fiziki
Language(s) - English
Resource type - Journals
eISSN - 1726-748X
pISSN - 0044-4642
DOI - 10.21883/jtf.2020.07.49443.344-19
Subject(s) - misorientation , materials science , substructure , martensite , crystallography , nucleation , quenching (fluorescence) , alloy , electron backscatter diffraction , transmission electron microscopy , metallography , diffusionless transformation , ingot , metallurgy , grain boundary , microstructure , thermodynamics , optics , chemistry , nanotechnology , physics , structural engineering , engineering , fluorescence
By the means of metallography, scanning and transmission electron microscopy, and EBSD-analysis, the features of the structure formation upon β→α (fcc-hcp) - polymorphic transformation in Co - Nb binary alloys were studied. It was shown that upon gradual cooling of the crystallized ingot, in each β-grain of the alloy nucleation of the α-phase crystals of several orientations out of 4 possible in accordance with the Wasserman’s orientational relations occurs. The formation of any of the 4 possible orientations of the α-phase is equally probable. At room temperature, only α (hcp)-martensite was found in the structure of the studied alloys. The misorientation of the substructure in the martensitic crystals length-wise in cast alloys does not exceed 1 deg.After the homogenization and the subsequent quenching in salted water, the structure of Co-Nb alloys does not undergo neither morphological, nor crystallographic changes, but becomes noticeably more fine-grained. In this case, the misorientation of the substructure elements of the martensitic crystals length-wise increases several times, consequent to the high level of quenching microstresses in martensite. No phases with multilayer lattices such as NR martensite were found.