Hard X-ray transmission microscopy based on refractive X-ray optics can be employed as a tool in material science to investigate buried-in microstructures in two or three dimensions with spatial resolution approaching 100 nm. Switching from monochromatic to radiation with a broader bandwidth, frame rates down to a few milliseconds can be realized, opening new possibilities for in situ studies of microstructure evolution and response to external fields at spatiotemporal resolutions that go well beyond previous benchmarks, demonstrated by similar to 200 nm resolution tomograms of eutectic microstructures acquired in less than 2 s. The microscope can also be operated in Zernike phase contrast mode, which expands the range of possible applications to cases which otherwise would produce only very faint contrast. A few possible application areas for the microscope are illustrated by a selection of material science test cases.