Influence of Rare-Earth Additions on Properties of Titanium Alloys - Effects of Yttrium and Erbium Additions on Ti-8Al and Ti-10Al Alloy

摘要

The influence of additions of 0.05-1.0 wt% Y and 0.2-2.0 wt% Er on the microstructure, slip distribution, fracture modes, and room- and elevated-temperature mechanical properties of Ti-8Al and Ti-10Al alloys was studied. Additions of up to 0.1 wt% Y and 0.2 wt% Er result in 50-200 nm incoherent dispersoids which effect grain refinement, reduce the planarity of slip, and significantly increase the ductility of Ti-8Al alloys. The additions further improve the room-temperature fracture toughness and room- and elevated-temperature low-cycle fatigue life of Ti-8Al and do not significantly alter the creep of Ti-8Al and Ti-10Al alloys. Higher amounts of Y and Er additions produce large, 1-5 micron dispersoids and produce no significant grain refinement or improvements in strength and ductility of the alloys.