Fig. 1 XRD patterns of the alloys after ageing at 500 C

Fig. 2 Microstructures of the alloys after ageing at 500 C: a ME-SA, b 17-4PH

Fig. 3 TEM images of the solidified ME-SA: a, b bright field images, c, d diffraction patterns of the particles and schematic diagram. The red solid circle represents BCC and B2. The yellow dot only represents B2

Fig. 4 TEM images of the ME-SA after ageing at 500 °C: a, b bright field images, c, d diffraction patterns of the particles and schematic diagram. The red solid circle represents the disordered BCC structure B2 and D03. The yellow dashed circle represents B2 and D03, and the blue dotted circle represents only D03

Fig. 5 a Microhardness evolution of the alloys after ageing at 440-530 °C; b compressive engineering stress-strain curves of the alloys after ageing at 500 °C

Fig. 6 Potentiodynamic polarization curves of the aged alloys in 15 wt% H2SO4 solution

Fig. 7 Nyquist plots of the aged alloys in 15 wt% H2SO4 solution

Fig. 8 XPS spectra of the passive films formed on the ME-SA after passivation for 1 h at + 0.4 VSCE in 15 wt% H2SO4 solution at room temperature: a Cr 2p3/2; b Fe 2p3/2; c Al 2p; d Ti 2p 3/2; e Mo 3d; f Co 2p3/2; g Cu 2p3/2; h Mn 2p3/2; i Ni 2p3/2; j O 1 s; k cationic fractions in the passive film