Research Regarding the Possibility of Obtaining Nitinol by Powder Metallurgy

Abstract

In the paper the obtaining of nitinol by pressing and sintering of a mixture of nickel and titanium powders is presented. The fabrication of NiTi alloys by powder metallurgy allows avoiding the usual problems related to classical casting obtaining methods (problems related to defects caused by segregation or excessive growth of the grains), it also assures an exact control of the chemical composition and offers the possibility of manufacturing a variety of components very close to their final shape. Although the advantages of manufacturing products by powder metallurgy are certain, the first research presented in this paper in the case of nickel and titanium powders have showed some unwanted aspects related to powder metallurgy processing which are yet to be resolved, that is, the high oxide content, the high content of secondary phases, also the difficulty of obtaining dense materials. The main conclusion is that it is imperative to do the sintering in a protecting system (if possible in vacuum), because of the high content of oxygen observed in the measured sintered products.