The enhanced tensile property by introducing bimodal size distribution of lamellar O for O+B2 Ti2AlNb based alloy

In this article, the bimodal lamellar size distributed Ti2AlNb based alloy was first introduced to enhance the tensile properties. The investigation indicated that the coarse lamellar O could be obtained when solution treated at O+B2 region and the thin lamellar O was emerged during the aging process. The volume fraction and mean thickness of the lamellar O could be well controlled by the heat treatment and the variations of those were analyzed quantitatively with the help of the image analysis software. The yield strength was sensitive to the thickness of lamellar O and it was close to be saturated when the thickness of lamellar O decreased to 140 nm. The advantage of the bimodal lamellar size distributed alloy can be concluded that firstly, the coarse lamellar O formed during solution process makes the alloy owns good elongation and secondly, the fine lamellar O precipitate during aging process strengthens the alloy. Compared to the single lamellar size distributed alloy owning the highest mechanical properties, the ductility of the bimodal lamellar size distributed alloy is still improved significantly although the strength only increases a little.