Ultrasound attenuation was measured in nickel specimens of about 30 mm diameter prepared using the high pressure torsion technique. The cold working process produced an equivalent shear strain increasing from zero at the center up to 1000% at the edge of the specimen. The fragmentation of the grains due to multiple dislocations led to an ultrafine microstructure with large angle grain boundaries. The mean value of the grain size distribution gradually decreased from ∼50 μm at the center to 0.2 μm at the edge. Laser pulses of 5 ns were employed for the excitation of broadband ultrasound pulses covering the spectral range of 0.1-150 MHz. The ultrasound pulses were measured from the opposite side of the specimen by means of an optical interferometer and a piezoelectric foil transducer in two experimental setups. The features of the detected signal forms are discussed. The absolute value of the attenuation decreases from the center to the edge of the specimen showing nearly linear frequency dependence. The variation of the phase velocity was measured in a 6 mm-thick high pressure torsion nickel sample, revealing a velocity increase from the center to the edge.

X-ray computed tomography (XCT) has become a very important method for non-destructive 3D-characterization and evaluation of materials. Due to measurement speed and quality, XCT systems with cone beam geometry and matrix detectors have gained general acceptance. Continuous improvements in the quality and performance of X-ray tubes and XCT devices have led to cone beam CT systems that can now achieve spatial resolutions down to 1 μm and even below. However, the polychromatic nature of the source, limited photon flux and cone beam artefacts mean that there are limits to the quality of the CT-data achievable; these limits are particularly pronounced with materials of higher density like metals. Synchrotron radiation offers significant advantages by its monochromatic and parallel beam of high brilliance. These advantages usually cause fewer artefacts, improved contrast and resolution.Tomography data of a steel sample and of two multi-phase Al-samples (AlSi12Ni1, AlMg5Si7) are recorded by advanced cone beam XCT-systems with a μ-focus (μXCT) and a sub-μm (nano-focus, sub-μXCT) X-ray source with voxel dimensions between 0.4 and 3.5 μm and are compared with synchrotron computed tomography (sXCT) with 0.3 μm/voxel. CT data features like beam hardening and ring artefacts, detection of details, sharpness, contrast, signal-to-noise ratio and the grey value histogram are systematically compared. In all cases μXCT displayed the lowest performance. Sub-μXCT gives excellent results in the detection of details, spatial and contrast resolution, which are comparable to synchrotron-XCT recordings. The signal-to-noise ratio is usually significantly lower for sub-μXCT compared with the two other methods. With regard to measurement costs "for industrial users", scanning volume, accessibility and user-friendliness sub-μXCT has significant advantages in comparison to synchrotron-XCT.