Mechanical synthesis of nanostructured titanium–nickel alloys

Abstract

The methods of mechanically assisted synthesis and mechanical alloying are used to obtain nanostructured TiNi shape-memory alloys. A stoichiometric mixture of Ti and Ni powders was subjected to intense mechanical treatment in a planetary ball mill. It was shown that after 30 h milling, the synthesis of the product with a mean particle size of 20–30 nm proceeded at 550 °C. XRD data show mainly the presence of TiNi, Ti 2Ni and TiNi 3 phases. Prolongation of the milling process up to 40 h leads to direct synthesis of a product with a similar phase composition. SEM and TEM analyses are used to study morphological changes of reagent and product particles in the course of mechanical treatment and after the synthesis of products. The mechanochemical synthesis routes are compared with the traditional method of thermal synthesis. The advantages of the mechanochemical methods of synthesis of nanostructured products and obtaining Ti–Ni powders with a high sinterability are also discussed. It was shown that after cold pressing and sintering at 800 °C, compacts containing even distributed pores with a mean size of 1 μm were obtained. TiNi bodies with similar structural peculiarities are suitable for the purposes of implantology.