Microstructure of Superplastic Alloys Based on Ti–Nb for Medical Purposes

Vacuum-arc remelting with a nonconsumable electrode is used to prepare ingots of superelastic alloys Ti–22Nb–6Ta, Ti–22Nb–6Zr, and Ti–22Nb–3Ta–3Zr (at.%) that are studied by light and scanning electron microscopy. It is established that the microstructure of all alloys has fundamental differences. Ingots of all of the alloys develop limited dendrite liquation. A dendritic structure predominates in the upper part of each ingot whereas in the lower part there is a uniform grain structure. These regions are separated by a thin transition layer combining elements of both structures. It is shown that the average chemical composition of the alloys obtained corresponds to that prescribed.