The TTT-curve of an amorphous titanium alloy (Transformation-Time-Temperature)

Features of the transformation from the amorphous state to the equilibrium crystalline state of the titanium-base amorphous alloy Ti66Ni20Cu10Si4 are investigated, and it is shown that an analysis of the TTT-curve may serve as the basis for selection of the optimum cooling conditions of the molten metal to obtain the amorphous state. A TTT-curve was constructed using methods of physicochemical analysis, and differential thermal analysis curves, the elastic characteristics, and the electrical resistance were recorded in the 293-950 K range in heating at rates of 1, 10, and 25 deg/min. The elastic characteristics, the electrical resistance, and the microhardness of the alloy did not change after preliminary cooling in liquid nitrogen or after annealing at 313 and 353 K. Results of microstructural and X-ray diffraction analyses show that the amorphous state is preserved of strip samples up to 150 microns thick. The structure of samples 440 microns thick and more was completely crystalline.