This data was collected to study the isothermal coarsening of faceted Si particles in an Al-Si-Cu liquid. The as-cast, hyper-eutectic sample consisted of primary Si particles in a eutectic matrix. Upon heating to above the eutectic temperature (here, 650 C), the eutectic constituents melted and the Si particles were in contact with a featureless liquid. Tracking the evolution of the solid-liquid interfaces under isothermal conditions was the focus of this work. The raw data were obtained in the following sequence: (i) for the first 60 time-steps (i.e., 3D reconstructions), projections were collected continuously using 1000 projections per 180 degree revolution and a rotation rate of 9 degrees per s; (ii) for the next 20 time-steps, scans were spaced 1 min apart, using 3000 projections and a rotation rate of 3 degrees per s; (iii) for the following 20 time-steps, scans were spaced 5 min apart using the same imaging parameters; (iv) for the last 5 time-steps, the interval between scans increased to 11 minutes, using the same imaging parameters as in (ii)-(iii). Thus, a total of 105 reconstructions were collected over the course of 5 hours, where each reconstruction captured the average microstructure in a 20 s window. The motivation for collecting the X-ray projections in this manner was that the system-average length-scale increased logarithmically with time during coarsening. Therefore, this data collection scheme adequately captured the interfacial dynamics. The data here includes the raw projections. Note that dark field and flat field measurements, which are used to normalize the data, are in a separate file. For details on the data processing and quantitative analysis, the reader is pointed to the following publication. Correspondence should be directed to Ashwin J. Shahani (shahani@u.northwestern.edu).