Abstract
A Detailed Transmission Electron Microscopy (TEM) Study Has Been Made of the Ageing Hardening Behavior of the γ1-Ti4Nb3Al9Precipitation Phase in the γ-TiAl Matrix in Ti-Al-Nb System. it Is Revealed that the γ1-Ti4Nb3Al9Precipitate, which Is Formed by a Normal Quench at 1473k and Ageing Treatment at 1073K, Takes Needle-Like Morphology with a Growing Axis Parallel to [001] Direction of the Matrix. the Needle-Like Precipitates Act as Barrier Grid to Inhibit Dislocation Moving on the Slipping Plane {111} of the γ-TiAl Matrix, which Helps to Improve the Strength of the Alloy. the Effects of the Third Element Niobium to the Strengthen of High Nb Containing TiAl Alloys Lie in Not only Solid Solution, but Also Ageing Hardening. the Interfaces between Precipitate and Matrix Are Also Investigated.
Publisher
Trans Tech Publications, Ltd.
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