Damages of TZM as plasma facing material under transient heat load

•The partial melting area in the in-situ melting TZM tile is like an impact pit, which causes the melted liquid droplets in the melting area to splash around, while ex-situ melting TZM does not have this feature.•The number and width of cracks in the in-situ TZM brick are more than those in the ex-situ test TZM tiles. Meanwhile the crack extension directions in the in-situ melting TZM tile are various, while those features on the ex-situ TZM tiles is single.•The capillary waves around the castle structure in the test samples are the result of the wetting effect of liquid metal and capillary force, and the holes in the re solidified layer are caused by the overheating boiling of TZM liquid.