This paper demonstrates a non-destructive technique to evaluate the internal microstructure in the Sn-Ag-Cu (SAC) solder joint through synchrotron X-ray radiation tomography. Synchrotron X-ray tomography is increasingly utilized for characterizing the internal microstructure of materials in 3D images. A 3D model is reconstructed from a set of 2D projection images taken from different angles and angular position during the sample rotation, thus it could provide a more comprehensive description of the microstructure of an alloy compared to 2D images. In this paper, it is successfully observed and evaluated the internal microstructure of a 900 μm solder joint sample. The key principles and methods of synchrotron X-ray tomography are briefly described. Examples of quantitative and qualitative assessments on the grain refinement effect of Mg addition to SAC35 solder joint are also presented in this paper.

Dolomite can be used as a source of aluminosilicate to produce geopolymers; however, this approach is limited by its low reactivity. This study analyzes the viability of producing geopolymers using dolomite/fly-ash with sodium silicate and NaOH solutions (at multiple concentrations) by determining the resultant geopolymers’ compressive strengths. The dolomite/fly-ash-based geopolymers at a NaOH concentration of ~22 M resulted in an optimum compressive strength of 46.38 MPa after being cured for 28 days, and the SEM and FTIR analyses confirmed the denser surface of the geopolymer matrix. The synchrotron micro-XRF analyses confirmed that the Ca concentration exceeded that of Si and Mg, leading to the formation of calcium silicate hydrate, which strengthens the resulting geopolymers.