Criteria for fast and selective α precipitation at β grain boundaries in Ti-alloys Consequence for in-service microstructures

Tao Liu (1, 2) , Lionel Germain (1, 2) , Julien Teixeira (3, 2) , Elisabeth Aeby-Gautier (3, 2) , Nathalie Gey (1, 2)

1 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
2 Labex DAMAS
3 IJL - Institut Jean Lamour

The potential for β grain boundaries (GBs) to give rise to large Widmanstätten colonies was determined through the observation of a large amount of precipitates at β GBs in a β-metastable titanium alloy using electron backscatter imaging and diffraction. The most critical boundaries are those which transform early and where a type of Variant Selection (VS) called double Burgers VS occurs. This mechanisms take place at 'special' β boundaries misoriented so that an α precipitate can be related to both grains through the Burgers relation. It was shown that the most critical GBs have a disorientation at an angle of less than 10° from 49.5°/<110> or 60°/<110>. A simulation study allowed those boundaries to be quantifed in crystallographic textures typical of industrial products. Those texture have then been discussed as a function of their potential to form large Widmanstätten colonies.

Keywords: titanium; Variant selection; Grain boundary; Texture

Domains: Engineering Sciences [physics]; Engineering Sciences [physics]; Materials; Engineering Sciences [physics]; Mechanics [physics.med-ph]

Tao Liu, Lionel Germain, Julien Teixeira, Elisabeth Aeby-Gautier, Nathalie Gey. Criteria for fast and selective α precipitation at β grain boundaries in Ti-alloys Consequence for in-service microstructures. The 14th World Conference on Titanium, Jun 2019, Nantes, France. ⟨10.1051/matecconf/202032112040⟩. ⟨hal-02380889v2⟩