Synchrotron X-ray study of bulk lattice strains in externally loaded Cu-Mocomposites

A synchrotron X-ray transmission technique was applied to study the interna l load transfer and micromechanical damage in molybdenum particle-reinforce d copper matrix composites during plastic deformation. Mechanically loaded, 1.5-mm-thick specimens were irradiated with a monochromatic beam of 65 keV X-rays. Low-index diffraction rings of both phases were recorded with a hi gh-resolution two-dimensional detector. By means of newly developed data pr ocessing routines, we could quantify as a function of applied stress both t he ring distortion (from which the volume-averaged elastic strains in the t wo phases were calculated), and the ring graininess (which is related to th e Bragg peak broadening). Based on this information, the deformation and da mage processes in these alloys were studied in detail. As compared to conve ntional neutron diffraction methods, the photon transmission technique yiel ded similar precision but at much reduced measurement times. The main sourc es of experimental errors were identified and strategies to minimize these errors were developed.