Friction Stir Additive Manufacturing: Neutron Interferometry and Bragg Edge Imaging
摘要
The layered structure of aluminum 6061 cross-sections was studied with several neutron imaging methods: transmission, grating interferometry (dark field), and Bragg-edge imaging. The multilayered samples were prepared by additive friction-stir deposition (AFSD) of aluminum 6061 with 2.54 mm print layer thickness. The AFSD aluminum printing was done in air; no evidence of aluminum hydroxide impurities was found in the neutron transmission images. The neutron dark-field data, however, showed a distinct layering structure that was affected by post-build annealing. These measurements used Talbot-Lau interferometry at a cold-neutron beamline without a monochromator and fitted, in favorable cases, to a single scattering model. Anisotropic scattering in the 6061 build plate was noted and measured. The neutron Bragg-Edge images showed crystal grain alignment in patterns correlated with the AFSD tool path.