INFLUENCE OF HIGH-ENERGY MILLING IN HYDROGEN ON THE STRUCTURAL-PHASE STATE OF ALLOYS BASED ON THE LAVES PHASES

The influence of high-energy milling in a planetary mill in the atmosphere of hydrogen on the structure and phase composition of alloys based on the Laves phases is analyzed. We study ZrMn2 and ZrCrNi alloys containing an MgZn2-type hexagonal Laves phase in the initial state. The changes in the phase- and-structural states of these alloys after milling in hydrogen and thermal treatment in a vacuum are studied with the help of scanning electron microscopy, electron-probe microanalysis, and X-ray phase-diffraction analysis. It is shown that, under the conditions of milling in hydrogen, the main phases of the ZrMn2 and ZrCrNi alloys decompose into zirconium hydride and manganese and into zirconium hydride and chromium, respectively. As the duration of milling increases, the iron content of the samples becomes higher as a result of wear of the milling balls. Depending on the duration of milling, the phases with MgZn2- or Th6Mn23-type structures are formed in the ZrMn2 alloy after heat treatment in a vacuum. At the same time, the Mg Cu-2 - and Th6Mn23 -type phases are formed in the ZrCrNi alloy.