[en] Experiments are performed to investigate the fragmention mechanism. Main features of the experiment are the use of a highspeed movie camera with the maximum recording frequency of 100 000 frames per second which is about 20 times the recording frequency of conventional highspeed movie cameras and the application of an external trigger to induce the fragmentation. The material combination copper/water is employed and experiments are carried out in the normal atmosphere and in two reducing atmospheres. The highspeed movie camera employed enabled a detailed phenomenological observation of the fragmentation process which in this manner had not been performed prior to this experiment due to the extremely short fragmentation time (1 ms). Two types of fragmentation, delayed and prompt fragmentation, were identified. The occurance of the delayed and prompt fragmentation, respectively, is governed by two parameters, the temperature of the hot melt and the magnitude of the triggerpuls. A threshold is identified which can be described as a function of the two parameters mentioned above. These observations can be explained with the change of the surface tension of the hot melt which is influenced by the atmosphere in which experiments are carried out. Based on these facts a phenomenological model of the fragmentation mechanism is proposed. (orig.)