Niobium deuteride samples are exposed to vacuum sparks with plasma temperatures exceeding 10 keV and a density of >1023 cm−3. An investigation of the surfaces of the niobium deuteride samples by scanning electron microscopy reveals clear signs of surface melting, orifices, bubbles, blisters, and cracks. The surface features are explained in terms of a very high vapor pressure of deuterium forming in niobium at temperatures near its melting point. Vacuum sparks touching the surfaces for ∼1 µs may expel most of the deuterium from the surface region.