Особенности кристаллизации аморфных сплавов TiNiCu с высоким содержанием меди

Alloys of the quasi-binary TiNi – TiCu system with a copper content of 25, 30, 35, and 40 at. % were obtained by planar flow casting technique at a cooling rate of 10^6 K/s in the form of ribbons 30–50 μm thick and 10–20 mm wide. The structure and phase transformations in the alloys were studied using electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry. It was found that in the initial state, the alloys with 25 and 30 at.% Cu have an amorphous-crystalline structure, undergoing a one-stage polymorphic crystallization of the amorphous state on heating in a calorimeter with the formation of austenite B2 phase, which on cooling to room temperature proceeds to orthorhombic B19 phase due to the martensitic transformation. It is shown that the alloys with 35 and 40 at.% Cu at quenching become amorphous, and upon heating, two-stage crystallization occurs (primary and eutectic) with the formation of a two-phase structure - the tetragonal B11 (TiCu) phase with a small fraction of B2 phase. Moreover, an increase in the copper content leads to a decrease in the onset temperature of crystallization.

Features of the Formation of Structure and Phases in Single-Crystal High-Temperature Alloys and their Effect on Mechanical Properties

Features of the structure and phase transformations in single-crystal nickel alloys 1, 2 after long high-temperature exposures were considered in this paper. The results and studies of the residual mechanical properties of alloys after exposure are given. Nanophase hardening of single-crystal heat resistant nickel alloys was also considered. The method of heat treatment of single-crystal high-temperature nickel alloys was developed based on the studies. It provides an increase in the strength properties of alloys by 20...30%, due to the formation of bulk nanophases (γn+ γ'n). The data obtained on structural and phase changes in high-temperature nickel alloys make it possible to evaluate the stability of the structural state of alloys.