Peter K. Liaw, University of Tennessee Knoxville, DMR 0421219

1. Major Research Instrumentation (MRI): Development of an In-Situ Neutron Scattering Facility for Research and Education in the Mechanical Behavior of Materials Peter K. Liaw, University of Tennessee Knoxville, DMR 0421219 To complement the development of an in-situ neuron scattering facility at Spallation Neutron Source (SNS), Oak Ridge National Laboratory, Tennessee, preliminary experiments using diffractions were conducted to study the mechanical behaviors of nanocrystalline (nc) materials. • Specimen: • Nc Ni-18wt.%Fe alloy (wt.%: weight percent) (Ni-18Fe) • Mechanical experiments: • 1. Rolling deformations performed at both room temperature (RT) and liquid-nitrogen temperature (LNT). • 2. Diffraction experiments • Diffraction-analysis methods: • Qualitative method: modified William-Hall method1 • Quantitative method: diffraction line-profile analysis (performed by convolutional-multiple-whole-profile (eCMWP) programs. (a) (b) Figure 1(a) Comparison ofdiffraction patterns for the as-deposited, RT-rolled, and LNT-rolled nc Ni-18Fe alloys shows that peak-widths are shrinking after rolling deformation at both RT and LNT. (b) Modified William-Hall plots quantitatively show the increased grain size [reciprocal to the full-width at half-maximum (FWHM) intercept] and decreased dislocation density (proportional to the slope of line). Table 1. The eCMWP fitting values for the average dislocation density (), area-averaged mean crystallite size (<x>area), and twin-boundary frequency () of the as-deposited, RT-rolled, and LNT-rolled nc Ni-18Fe alloys, respectively. It clearly shows the dislocation density and twin-boundary frequency decreased concomitantly with grain growth. New findings: Concomitant reductions in the densities of both dislocations and twins and an increase in the crystallite size, which has never been observed before.

2. Major Research Instrumentation (MRI): Peter K. Liaw, University of Tennessee Knoxville, DMR 0421219 Development of an In-Situ Neutron Scattering Facility for Research and Education in the Mechanical Behavior of Materials Outreach Activities • Prepared a talk for The 2008 Mineral, Metals & Materials Society (TMS) at New Orleans. • Participated in the 2008 TMS Outstanding Student Paper Contest. • International Collaborations • Worked with Prof. Ungar from Eötvös University, Hungary, on analyzing diffraction patterns for about 6 weeks at The University of Tennessee in March and April 2008. • Li Li will visit Prof. Ungar’s Lab at Budapest, Hungary, and learn diffraction line-profile analyses to continue the collaboration. • Prof. Ungar • Li Li A photo taken during Prof. Ungar’s 6 weeks’ visit at The University of Tennessee in Spring 2008