The Microstructureand Mechanical Properties Of Ti-47al-(2,5)Nb Influenced By Y, Gd And Er

Ti-47Al-2Nb and Ti-47Al-5Nb alloy with the addition of rare earth Y, Gd, Er were prepared with the equipment of non-consumable tungsten electrode smelting furnace. The microstructure and fracture surface obtained by compression were observed using OM and SEM. Mechanical properties were tested by Instron5569 Universal Electronic Tensile Tester and digital readout low load Vickers hardness tester. The microstructure and mechanical properties of Ti-47Al-2Nb and Ti-47Al-5Nb alloy were researched systematically. Here are the results:The formationheat and activity coefficient among the compounds were calculated by Miedema model. The physical property parameter of rare earth elements Y, Gd, Er is very similar. When they react with other compounds their formationheat and activity coefficient is also close to each other.This paper researched the influence of microstructure and mechanical properties under the action of rare earth Y of Ti-47Al-2Nb and Ti-47Al-5Nb alloys. It finds that the Ti-47Al-2Nb and Ti-47Al-5Nb alloys'primary and secondary dendrite arm spacing become finer with the more Y addition and the degree depends on the addition of Y. Ti-47Al-2Nb-0.3Y alloy has the best mechanical properties, such as: stress, strain and hardness.The influence of Gd to the microstructure and mechanical properties of Ti-47Al-2Nb and Ti-47Al-5Nb alloys were researched. The relationship between the precipitates'type, morphology and the deoxy effection and Gd addition were analysised. It's the 0.15at.% Gd that Ti-47Al-2Nb and Ti-47Al-5Nb alloys has the best properties due to its refining grain. When the addition of Gd is 0.3at.% the alloy'microstructure becomes coarser and has the worse properties.The microstructure and mechanical properties'influence with the addition of Er to Ti-47Al-2Nb and Ti-47Al-5Nb alloys were analysised. The primary and secondary dendrite arm spacing grows smaller as the more Er. Ti-47Al-5Nb-0.2Er alloy has the best properties in the aspects of compression properties, hardness and fracture surface.