Investigation of the structure and phase composition of Ti and Nb powders after mechanical activation

Features of structure and phase composition of the powders of Ti and Nb after mechanical activation are investigated by the methods of X-ray diffraction, scanning electron microscopy and energy-dispersive microanalysis. The powders were mixed in mass ratio 60 % Ti and 40 % Nb in planetary mill AGO-2C during 10, 15 and 20 minutes. Water-cooled camera was used to reduce the temperature of the process. It is shown that during the process of mechanical activation the powder of two-component composition is obtained. During the process of severe plastic deformation and mixing particles of Ti and Nb are combined into larger objects. The agglomerates with scale structure are formed. The size distribution of powder particles is characterized by bimodal type. Most particles have a size from 10 to microns. A smaller part of formed particles has a size of about 100 microns. As a result of treatment time increasing the scatter of the powder granulometric composition is reduced with shifting to lower values. It was observed that during activation time increase the content of Nb saluted in Ti increases and reaches composition Ti37Nb at 20 minutes of activation. Ti and Nb are equilibrium distributed inside the particles. Herewith the main beta-phase forms rom phases of initial components. beta-phase is the substitutional solid solution of Ti and Nb. The beta-phase quantity increases with the activation time increasing. The phase of initial alpha-Ti is retained in the alloy throughout the treatment time. Increasing of treatment time or using of additive factors which enhance the effect of mechanical activation is necessary to complete the process of monophase alloy formation. It is shown in conclusion that the form and granulometric composition of obtained Ti-Nb alloy powder, its phase composition with equilibrium distribution of components allow use it in additive technology of selective laser sintering.