Locally resolved stress and strain analysis of sinter-joined micro valves using synchrotron X-ray diffraction and conical slit apertures

For assessing the quality of the joining area as well as researching the influence of joining parameters in combination with different materials, the principal stress components of sinter-joined micro valves were analysed. Transmission experiments have been conducted at the high-energy material science (HEMS) beamline P07 at PETRA III, DESY. Due to the dimensions of the samples, a high spatial resolution of the measurements was required. Of special interest was the distribution of residual stress in the joining area of the valves, which demanded a depth resolved measurement using a conical slit. Strains were deduced from the obtained Debye–Scherrer rings of the {200}, {211}, and {220}-planes of the α/α′-phase involving reference measurements on non-sintered powder of the specimen materials. The grain statistics have been improved by integrating over slices of the diffraction rings and by calculating a mean lattice parameter taking into account all lattice planes. From the strain data, the hydrostatic and the deviatoric stress were calculated for the three dimensional stress state.