Isothermal annealing of thin rolled tungsten plates in the temperature range from 1300 °C to 1400 °C

The annealing behavior of thin tungsten plates of four different thicknesses achieved by warm- and (in two cases) cold-rolling is investigated. Isothermal experiments at five different temperatures between 1300 °C to 1400 °C were performed. Hardness testing of annealed specimens allowed tracking the degradation of the mechanical properties and, indirectly, the microstructural evolution. Supplementary microscopical investigations of the microstructure in the as-received state as well as after annealing were performed to characterize the initial condition and to support the identification of the involved restoration processes. All four tungsten plates undergo microstructural restoration by recovery and recrystallization. The observed differences in their behavior were rationalized in terms of the identified differences in the microstructure in the as-received state, rather than their different initial thickness. Keywords: Tungsten, Annealing, Recrystallization, Thermal stability, Hardness testing, EBS

Effects of Initial Parameters on the Development of Cube Texture during Recrystallization of Copper

A series of oxygen free high conductivity copper samples with different initial grain sizes, cold rolling conditions and storage times as well as slightly different impurity contents was used to investigate the effects of these initial parameters on the development of cube texture during recrystallization. For rolling reductions of 90% and 95%, cube textures with volume fractions between 3% and 50% were observed. Higher rolling reduction led to a stronger cube texture. Cube texture development is very sensitive to the initial grain size before rolling. In general, fine grained material gives a strong cube texture after recrystallization, and the requirement on fineness of the grain size may vary for materials with different purity. Large sample widening during rolling can largely inhibit the development of cube texture after recrystallization. Neither storage time, nor the slight change in impurity content had large effects in the present investigation.</jats:p

In-situ investigations of structural changes during cyclic loading by high resolution reciprocal space mapping

A major failure reason for structural materials is fatigue-related damage due to repeatedly changing mechanical loads. During cyclic loading dislocations self-organize into characteristic ordered structures, which play a decisive role for the materials lifetime. These heterogeneous dislocation structures can be identified using advanced electron microscopy and synchrotron techniques. A detailed characterization of the microstructure during cyclic loading by in-situ monitoring the internal structure within individual grains with high energy x-rays can help to understand and predict the materials behavior during cyclic deformation and to improve the material design. While monitoring macroscopic stress and strain during cyclic loading, reciprocal space maps of diffraction peaks from single grains are obtained with high resolution. High Resolution Reciprocal Space Mapping was applied successfully in-situ during cyclic deformation of macroscopic aluminium samples at the Advanced Photon Source to reveal the structural reorganization within single grains embedded in the bulk material during fatigue