FEATURES OF STRUCTURE, SUBSTRUCTURE, AND RESIDUAL STRESS OF Ti41.5Zr41.5Ni17 QUASICRYSTALS QUENCHED FROM LIQUID STATE

Abstract

The structural state, stress, and substructure parameters of ribbons obtained by rapid solidification from the liquid state of the Ti41.5Zr41.5Ni17 alloy and powders obtained by deformation were investigated using X-ray diffraction and SEM microscopy methods. The influence of sample preparation parameters such as quenching rate and intensity of deformation, on the content of the Ti41.5Zr41.5Ni17 quasicrystalline phase and the crystalline phase of the approximant (W-phase), is considered. It is noted that the volume content of the W-phase increases with higher deformation intensity and decreases with higher quenching rate. Accumulation of specific defects in the quasicrystalline structure, known as phason defects, occurring during quenching, is observed in ribbon samples. The concentration of phason defects is nonuniform over the cross section of the samples, increasing from the side of the ribbon in contact with the quenching wheel to the free surface. This non-uniformity may be associated with the participation of phason defects at the initial stage of the phase transformation during the formation of the W-phase. The concentration of phason defects significantly increases during deformation of ribbons.