No abstract

No abstract

Highlights  Residual stress and phase analysis at the microscale at interface and coping edge  X-ray diffraction and Raman spectroscopy show comparable results  Cross validation using ring-core focused ion beam and digital image correlation  Monoclinic and highly stressed regions identified close to interface  Phase transformation volumetric expansion is the origin of porcelain failure

Full In-plane Strain Tensor (FIST) analysis at the micro-scale is crucial for improving the evaluation of residual stress and the understanding of the origins of mechanical failure in many applications ranging from civil structures to energy systems and micro-electronics. This study presents the analytical background and experimental implementation of a Focused Ion Beam (FIB) milling and Digital Image Correlation (DIC) based technique that uses material removal and strain relief monitoring to perform precise, reliable and rapid quantification of micro-scale residual stress.The nature of semi-destructive FIB milling overcomes the main limitations of X-Ray Diffraction (XRD) strain tensor quantification: unstrained lattice parameter estimates are not required, analysis is performed in within a precisely defined 3D microscale volume, both amorphous and crystalline materials can be studied and access to X-ray/neutron facilities is not required.The FIST FIB milling and DIC experimental technique is based on extending the interpretation of strain relief observed for the ring-core milling geometry to quantify the strain variation with azimuthal angle. The approach benefits from the high magnitude of strain relief, excellent precision and the simplicity of the analytical approach associated with this method. In-plane strain analysis is reported for a sample of commercial interest: a porcelain veneered Yttria Partially Stabilised Zirconia (YPSZ) dental prosthesis, for which the results were also compared with micro-beam synchrotron X-ray diffraction. Since the two methods sample different gauge volumes and mechanical states (approaching plane stress for ring-core milling and through-thickness averaging that approaches plane strain for XRD), the important matter of correlating the two sets of measurements arises and requires addressing. Complex variable and Finite Element (FE) methods are used to connect the two states, demonstrating that valid comparisons can be drawn. The analysis revealed excellent agreement between the principal stress orientation and values, led to realistic residual stress estimates which closely matched literature measurements ( ≈ 460 MPa) and produced upper and lower bounds for the (101) interplanar crystal lattice spacing of YPSZ in the range 2.9586 − 2.9596 Å, closely matching published values. Highlights• Full in-plane strain tensor measured by ring-core Focused Ion Beam (FIB) milling• Absolute strain measurement at the μm-scale for amorphous & crystalline materials• Comparative X-ray diffraction study validates experimental FIB results• Lattice parameter and stress state in Zr prosthesis sample match literature values• Surface vs bulk residual stress state relationships was identified and validated

No abstract