DIFFERENCES IN THE LOCAL ATOMIC STRUCTURE OF THE AMORPHOUS TI₂NICU ALLOYS PRODUCED BY MELT QUENCHING AND LARGE PLASTIC DEFORMATIONS

At present, systematic studies of structural regularities inherent in metallic materials in the process of large plastic deformations are actively proceeding. In particular, by high-pressure torsion, the authors obtained many interesting and important results. It is known, that some alloys and intermetallic compounds during the high-pressure torsion change from a crystalline to an amorphous state. However, in the literature, there is no answer to the issue of similarity or difference in the local structure of amorphous states of the same alloy produced by various methods (after melt quenching and high-pressure torsion). In the paper, using the EXAFS spectroscopy, X-ray diffraction analysis, and transmission electron microscopy, the authors studied the local atomic structure of the amorphous Ti₂NiCu alloy produced by melt quenching and high-pressure torsion. It is shown that the local atomic structure of the amorphous phases produced by melt quenching and high-pressure torsion is not identical. The amorphous structure of the Ti₂NiCu alloy produced by the high-pressure torsion compresses and becomes improved under the action of significant deformation effects as the strain increases at room temperature to n =6. The authors identified that the radii of the first coordination spheres of pairs of atoms of the Cu-Ti and Ni-Ti types, as well as the corresponding coordination numbers, depend on both the method of obtaining the amorphous state and the value of high-pressure torsion. The interatomic Cu-Ti and Ni-Ti distances slightly increase after high-pressure torsion at n =4 compared to the state after melt quenching. The increase in the strain up to n =6 causes the decrease in the interatomic Cu-Ti and Ni-Ti distances as compared to the state after melt quenching.

amorphous state, melt quenching, large plastic deformation, high pressure torsion, phase transformation, amorphization