Quantitative analysis of effect of heat treatment on microstructure and microhardness of Ti2AlNb alloy

The microstructural features of B2 phase region isothermally forged Ti-22Al-25Nb (at%) orthorhombic alloy during heat treatment were quantitatively investigated. The volume fraction of the each phase, the width and length of the primary coarse lamellar O phase and secondary fine lamellar O phase in the alloy at different heat treatment temperatures were measured by image analysis software. The relationship between microstructure parameters and microhardness was analyzed with a multiple regression analysis technique. The results indicate that the microstructure of this alloy is mainly depended on the heat treatment schedule. The width of primary coarse and secondary fine lamellar O phase, and volume fraction of total precipitates can be controlled. Experimental and statistical results show a great linear relationship between the microstructure parameters and microhardness.