NONMONOTONIC CHANGE OF THE COMPOSITION OF SURFACE LAYERS OF THE MELT Co <sub>57 </sub>Ni <sub>10</sub>Fe <sub>5</sub>Si <sub>11</sub>B <sub>17</sub> DURING ISOTHERMAL PROCESS
XPS study of the surface layers composition of Co <sub>57</sub>Ni <sub>10</sub>Fe <sub>5</sub>Si <sub>11</sub>B <sub>17</sub> alloy in liquid state at temperature change and during isothermal process is carried out. In the melt jump-like changes of the surface layers composition are detected, they are interpreted as the structural transformations in the liquid state. Nonmonotonic behavior of the surface layers composition of Co <sub>57</sub>Ni <sub>10</sub>Fe <sub>5</sub>Si <sub>11</sub>B <sub>17</sub> melt (criterion Co/Fe) is detected during isothermal process. Most instability of the melt is observed in the structural transformation region.