Orientation Dependence of Microstructure and Defect Accumulation in Textured Materials

EMANUEL BENATTI; R. E. BOLMARO; M. C. AVALOS; N. S. DE VINCENTIS; N. SCHELL; ZHENGYE ZHONG; H.-G. BROKMEIER

Cancún

Congreso; XXV International Materials Research Congress; 2016

MRS

Massive data obtained through transmission high-energy x-rays are information intensive and quite difficult to be analyzed without using large computational and physic models. However, they should carry enough information to allow a detailed analysis of microstructures, grain sizes, dislocation and twin densities in function of crystal orientations. Simple systems, for instance cubic materials with mainly one-component orientation distribution functions, are good candidates to explore the capabilities of existent computational/physic models to get a whole landscape for the defect accumulation phenomena in deformed materials.The current work shows results obtained in commercial Cu and Al alloys with strong starting cube texture, later deformed by rolling without losing the general distribution pattern.The experiments were carried out at the synchrotron facility in HEMS outstation, Petra III, DESY, Hamburg, Germany. An 87 KeV high-energy x-ray beam, with a size of 100 µm x 100 µm, was used in transmission mode to obtain whole plate Debye-Scherrer images in a solid state Mar3450 detector. The data was collected in 36 rotation positions around the vertical axes, what allows the determination of textures and the study of a large number of diffractograms in cake-sections of the images. Convolutional Multiple Whole Pattern model (T. Ungar et al., Budapest, Hungary) was implemented in a batch-processing program to fit 2592 diffractograms taken from seventy-two 5o cakes for each of the 36 image plates. Seed values for the starting parameters were obtained by the individual fit of a single diffractogram. The program was run in a parallel computer array, allowing faster processing.Both, Cu and Al systems, show a strong correlation between sample orientation and grain sizes and crystal orientation and dislocation density accumulation. The results are interpreted in terms of the development of dislocation arrays, grain fragmentation and plastic anisotropy.