The influence of hydrogen on the synthesis of biocompatible alloy Ti-6Al-7 Nb by a new Hydride Cycle method

Abstract

The Hydride Cycle (HC) method is proposed as a new approach for synthesis of biocompatible alloy Ti-6Al-7 Nb. In this approach, preliminary, (Ti-7 Nb)H3.81 hydride is synthesised by Self-propagating High-temperature Synthesis (SHS) method. The heating of a mixture of this hydride with aluminum, (Ti-7 Nb)H3.81+6Al, at 1000°C for 30 minutes in the HC device results in the synthesis of Ti-6Al-7 Nb alloy containing the α- and β-phases of Ti, 92 wt% and 8 wt%, respectively. The alloy interacted with hydrogen in the combustion mode (SHS) forming the hydride (Ti-6Al-7 Nb)H3.17 with hydrogen content 3.07 wt%. This amount of hydrogen ensures the brittleness of the hydride and its grinding for 30–40 minutes to the agglomerates down to submicron or nano sizes. The presence of hydrogen in the crystal lattice enhances the plasticity of the hydride facilitating its compaction. The compaction of the (Ti-6Al-7 Nb)H3.17 alloy hydride and dehydrogenation under T=1000°C results in the reaction-activated sintering and the formation of practically porous less Ti-6Al-7 Nb alloy. The HC synthesis of the biocompatible alloy Ti-6Al-7 Nb compiled with SHS mode of the hydride synthesis is provided with the several advantages over the traditional methods. It is a low temperature, short duration, waste less process, proceeding by solid-state mechanism without melting of components, being an energy-saving in total. The proposed HC approach for synthesis of Ti-6Al-7 Nb alloy in combination with the high-technology SHS process for the hydrides formation can be used in manufacturing the biocompatible alloys. The hydrogenation-sintering of the alloy hydride (Ti-6Al-7 Nb)H3.17 can be used for producing of items of any designed complex form, particularly of implants.