Ti-4Fe-7Al Alloy

Alloy name: Ti-4Fe-7Al
Diagram No.: 627
Type of diagram: TTT
Chemical composition in weight %: 3.92% Fe, 6.58% Al, 0.099% O, 0.013% Ni, 0.008% Cr, 0.003% C, 0.005% N, 0.0073% H, balance is Ti
Alloy group: Titanium-based alloys
Note: TTT diagram of tempered Ti-4Fe-7Al. A constant transformation fraction estimated from hardness shows a lower half C-curve.
The transformation behavior and microstructural changes of Ti-4Fe-7Al alloy during tempering were investigated by performing a hardness test and using X_ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Within a brief time of 30 s during tempering at 450 C, the hardness rapidly increased to a maximum value of 600 Hv. The transformation behavior estimated from the increase in hardness indicated a lower half of C-curve in the TTT diagram, which suggests that the transformation occurs through certain thermal activation processes. However, it is difficult to assume that the transformation is controlled by the diffusion of substitutional atoms, since the mean diffusion distance of Fe atoms during tempering at 300 C for 1 x 10 exp(3) s, which also maximized the hardness, is much less than the distance of the nearest neighbors in the beta structure. The structure of the alpha phase formed by tempering depends on both the temperature and holding time; a high temperature and a long time bring the alpha phase close to an hcp structure. As determined by XRD measurement, the sample tempered at 150 C for 60 min was composed of the beta phase. However, the omega and alpha phases were also detected in selected area diffraction (SAD) patterns. The sample tempered at 450 C for 60 min consisted of a single alpha phase and exhibited a tweed structure in the TEM observation. Although the tweed structure seemed to contain only one alpha variant in the SAD patterns, HR-TEM observation revealed that it was composed of multiple nanoscale variants. It was considered that the marked grain refinement due to the nanoscale variants led to the extreme hardening of the sample and the significant broadening of XRD peaks. When the tempering temperature was increased to 600 C, the a phase and finely dispersed TiFe precipitates were formed after 60 min by the diffusion of atoms, which resulted in the softening of the sample and the sharpening of the XRD peaks.
Reference: Not shown in this demo version.

Transformation Diagram

Price: 30.00 US $
Buy Online Transformation Diagram

Other Steel Data links
Carbides in Steel
Etchants Database
Hardenability Diagrams of Steels
Macro Defects in Steel
Non-Metallic Inclusions in Steel
Tempering Diagrams of Steels
CCT and TTT Diagram Calculating Service
Transformation Diagrams of Non-Ferrous Alloys

Disclaimer: The information and data presented herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his own evaluation and are not intended as warranties, either express or implied, of fitness for these or other puposes. There is no representation that the recipient of this literature will receive updated editions as the become available.

Copyright © 2019 by Steel Data. All Rights Reserved.