Quantitative Non-Destructive Detection of Residual Stresses of the 2 nd and 3 rd Order by Using Micro Magnetic Methods
Micro residual stresses (MRS) of the 2 and 3 order play an important role in the lifetime analysis of thermally-cycled materials. The coherent residual stresses (MRS of 3 order) appear when the lattice parameter of the second phase particles (coherently embedded in the matrix) and the lattice parameter of the matrix are different from each other. Such differences in case of the Fe-Cu alloys between the lattice parameters of coherent Cu precipitates and the lattice parameters of the αFe matrix lead to distortion of the lattice around the Cu particles causing coherent tensile MRS of 3 order. Thermally induced MRS of the 2 order appear when individual material phases exhibit different thermal expansion coefficients. Such differences in temperature-related expansion coefficients of copper precipitates and the α-Fe matrix promote the development of thermally induced compressive MRS of the 2 order. The main objective of the presented research project is to develop an integral, economical and fast micro-magnetic non-destructive method for quantitative characterisation of MRS of the 2 and 3 order in Fe-Cu and Fe-Cu-Ni alloys. For this purpose Fe-Cu and Fe-Cu-Ni alloy samples with different Cu and Ni contents were prepared.
Positron confinement in ultrafine embedded particles: Quantum-dot-like state in an Fe-Cu alloy
A quantum-dot-like positron state is demonstrated in the ``defect-free'' particles using coincidence Doppler broadening of positron annihilation radiation. The wave functions of all positrons are entirely confined spatially in all three directions within the embedded nanosize and subnanosize Cu particles in a dilute Fe-Cu alloy. With use of this probe, the ultrafine particles are revealed to have nearly the same electron momentum distribution as bulk Cu, to be free from Fe atoms and defects, three dimensional, and to have no open-volume defects at the interfaces which can trap the positron. These successes indicate that this positron state promises to be a powerful tool for the studies of mesoscopic systems in metals and semiconductors.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.