Effect of Zr on precipitation kinetics of Fe-Cr-Al alloys

Figures & data

Table 1. Chemical compositions of the designed Fe-Cr-Al alloys (wt.%, weight percent).

Alloys	Fe	Cr	Al	Mo	Nb	Ta	Zr
0.1Zr	bal	13.50	4.73	2.07	0.45	0.87	0.11
0.3Zr	bal	13.50	4.73	2.07	0.34	0.65	0.33

Figure 1. The OM of the S1-0.1Zr alloy (a) and S2-0.3Zr alloy (b), and the SEM secondary electron morphology of S2-0.3Zr after solid solution.

Figure 2. SEM images of the designed alloys at 1073 K aging for different time, (a, c, e): S1-0.1Zr alloy, (b, d, f): S2-0.3Zr alloy.

Figure 3. SEM images of the designed alloys at 1073 K aging for 12 and 24 h. (a, c, e): S1-0.1Zr, (b, d, f): S2-0.3Zr.

Figure 4. The average volume fraction (a) and the particle size (b) of the precipitates in the designed alloys during long-term aging at 1073 K.

Figure 5. The XRD patterns of the designed alloys after aging for 24 h.

Figure 6. TEM bright-field (BF) images and SAED patterns of the precipitated particles in the designed alloys at 1073 K, (a): S1-0.1Zr-5 min, (b): S2-0.3Zr-5 min, (c): S1-0.1Zr-24 h, (d): S2-0.3Zr-24 h; and the high resolution TEM image of the nano-precipitates in the S2-0.3Zr-5 min (e), and Laves in S1-0.1Zr-24 h (f).

Figure 7. HAADF image and the corresponding elemental maps of the 1073 K-aged S1-0.1Zr alloy by the Super-X EDS.

Figure 8. (a): Engineering stress–strain curves of the designed Fe-Cr-Al-M (M = Mo,Nb,Ta,Zr) alloys at 1073 K aging for 24 h, and (b): microhardness variation of the designed alloys at different states. The fracture surface morphologies of the alloys after aging for 24 h, (c): S1-0.1Zr, (d): S2-0.3Zr.

Figure 9. (a): lnln(1/(1-F))-lnt curves of precipitates in different alloys at 1073 K; (b): phase transformation kinetics curves of different alloys at 1073 K; (c): the precipitate rate changes with aging time and the microstructure evolution of different alloys; (d): variation of the mean particle radius r³ with the aging time at 1073 K for the designed alloys.