Features of crystallization of rapidly quenched Ni$_{45}$Ti$_{32}$Hf$_{18}$Cu$_{5}$ and Ni$_{25}$Ti$_{32}$Hf$_{18}$Cu$_{25}$ alloys from melt with high-temperature shape memory effect

A comparative study of the structure and the chemical and phase composition of Ni$_{45}$Ti$_{32}$Hf$_{18}$Cu$_{5}$ and Ni$_{25}$Ti$_{32}$Hf$_{18}$Cu$_{25}$ amorphous alloys obtained by fast-quenching of melt stream by spinning has been carried out by transmission and scanning electron microscopy and X-ray diffraction. The critical temperatures of their devitrification were determined by the data of temperatures measurements of electrical resistance. The features of the formation of ultrafine structure and the phase transformation at the vitrification depending on the regimes of heat treatment and chemical composition of alloy have been established.