SRF2011 - List of Authors (Baars, D.C.)

Paper	Title	Page
THPO067	Characterization of Large Grain Nb Ingot Microstructure Using OIM and Laue Methods	890
	D. Kang, D.C. Baars, T.R. Bieler Michigan State University, East Lansing, USA G. Ciovati JLAB, Newport News, Virginia, USA C. Compton FRIB, East Lansing, Michigan, USA T.L. Grimm, A.A. Kolka Niowave, Inc., Lansing, Michigan, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, through Grant No. DE-S0004222. Large grain niobium is being examined for fabricating superconducting radiofrequency cavities as an alternative to using rolled sheet with fine grains. It is desirable to know the grain orientations of a niobium ingot slice before fabrication, as this allows heterogeneous strain and surface roughness effects arising from etching to be anticipated. Characterization of grain orientations has been done using orientation imaging microscopy (OIM), which requires destructive extraction of pieces from an ingot slice. Use of a Laue camera allows nondestructive characterization of grain orientations, a process useful for evaluating slices and deformation during the manufacturing process. Five ingot slices from CBMM, Ningxia, and Heraeus are compared. One set of slices was deformed into a half cell and the deformation processes that cause crystal rotations have been investigated and compared with analytical predictions. The five ingot slices are compared in terms of their grain orientations and grain boundary misorientations, indicating no obvious commonalities, which suggests that grain orientations develop randomly during solidification.

Paper

Title

Page

Characterization of Large Grain Nb Ingot Microstructure Using OIM and Laue Methods

890

D. Kang, D.C. Baars, T.R. Bieler
Michigan State University, East Lansing, USA
G. Ciovati
JLAB, Newport News, Virginia, USA
C. Compton
FRIB, East Lansing, Michigan, USA
T.L. Grimm, A.A. Kolka
Niowave, Inc., Lansing, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, through Grant No. DE-S0004222.
Large grain niobium is being examined for fabricating superconducting radiofrequency cavities as an alternative to using rolled sheet with fine grains. It is desirable to know the grain orientations of a niobium ingot slice before fabrication, as this allows heterogeneous strain and surface roughness effects arising from etching to be anticipated. Characterization of grain orientations has been done using orientation imaging microscopy (OIM), which requires destructive extraction of pieces from an ingot slice. Use of a Laue camera allows nondestructive characterization of grain orientations, a process useful for evaluating slices and deformation during the manufacturing process. Five ingot slices from CBMM, Ningxia, and Heraeus are compared. One set of slices was deformed into a half cell and the deformation processes that cause crystal rotations have been investigated and compared with analytical predictions. The five ingot slices are compared in terms of their grain orientations and grain boundary misorientations, indicating no obvious commonalities, which suggests that grain orientations develop randomly during solidification.