Three-stage evolution of the structure and the effect of nonadditive hardening of layered composites of amorphous alloys under high-pressure torsion

The local chemical composition of composites consisting of alternating layers of Co$_{28.2}$Fe$_{38.9}$Cr$_{15.4}$Si$_{0.3}$B$_{17.2}$ and Fe$_{53.9}$Ni$_{26.5}$B$_{20.2}$ amorphous alloys subjected to torsion with increasing number of revolutions (true plastic strain) at high quasihydrostatic pressure in a Bridgman anvil cell is studied by time-of-flight mass spectroscopy. Three-stage transformation of the structure of composites with an increase in the strain is revealed. It is found that the average microhardness of the composite at a certain stage of machining exceeds the microhardness of its individual amorphous alloy components. The nature of the observed effects is discussed in terms of the features inherent in severe plastic deformations.