Comparison and optimization of texture evaluation techniques based on angle dispersive neutron diffraction and time-of-flight neutron diffraction

Xu, P. G.   ; Suzuki, Hiroshi  ; Metoki, Naoto   ; Akita, Koichi; Vogel, S. C.*; Nambu, Shoichi*; Inoue, Junya*

Compared with the X-ray diffraction, neutron diffraction is advantageous to measure complete pole figures of coarse-grained materials, to measure magnetic/residual strain/dislocation density/crystal size pole figures and it is also possible to investigate complex texture evolutions of bulk samples (rather than surfaces) of multiphase materials during heating, cooling and/or straining. Here, the crystallographic textures of high strength austenite-martensite laminated steel were measured with different neutron diffractometers. The comparison of orientation distribution functions showed that the Gaussian integrated intensities obtained from partially overlapping peaks were reliable to calculate the multiphase textures. Collimator optimized neutron beam and careful background correction enabled peak maximum intensities from non-overlapping peaks suitable to evaluate the multiphase textures. The Rietveld texture analysis of time-of-flight neutron diffraction spectra suggested that the spherical harmonic method and the E-WIMV discrete method were convincible up to an expansion series of L=12 and at a resolution angle of 10 degrees, respectively. In the near future, the development of time-of-flight texture measurement technique at J-PARC will be valuable to carry out the in situ texture evaluation while the introduction of 2-dimensional position-sensitive detector to the angle dispersive diffractometer will reduce the measurement time.