Fig. 1. Summary of the corrosion current densities of different alloys in NaCl solution under various hydrostatic pressures.

Fig. 2. (a) Polarization curves and (b) capacitance-potential curves of B10 alloy in 3.5% NaCl solution under 0.1 MPa and 6.3 MPa hydrostatic pressures [34].

Fig. 3. Polarization curves and the differential capacitance results for iron in (a, c) NaCl solution and (b, d) Na2SO4 solution, respectively [48].

Fig. 4. The calculated exchange current density modified by ψ1 effect at different hydrostatic pressures, for iron in 3.5% NaCl solution [48].

Fig. 5. Left panel: five NR measurements measured in 3.5% NaCl solution at different hydrostatic pressures. Solid curves are the fits corresponding to the SLD profiles shown in the middle and right panel. Right panel: magnified SLD distribution of the Al/Al2O3/liquid subphase region of the middle panel [51].

Fig. 6. . High-resolution bright-field TEM images of passive films formed at (a) 1 atm and (b) 80 atm. (c, d) Color-filtered TEM images of the two passive films. (e) Electron energy loss spectroscopy from the two passive films [52].

Fig. 7. The high-resolution HADDF images of the passive films formed on the outer surface of the top of the U-bend Ti-6Al-4V alloy in 3.5% NaCl solution after 0.25 V potentiostatic polarization. For the passive film prepared at 0.1 MPa hydrostatic pressure, (a) HADDF images along the [-24-23] direction of the α-Ti matrix and (b) along the [011] direction of the β-Ti matrix show a straight F/Me interface with slip steps. For the passive film prepared at 20 MPa hydrostatic pressure, (c) HADDF image along the [0001] direction of the α-Ti matrix shows a curved Me/F interface with slip steps, and (d) HADDF image along the [011] direction of the β-Ti matrix shows an undulating F/Me interface, where the slip steps disappear. Insets of panels (a-d) show the Fast Fourier Transform (FFT) images of the high-resolution HADDF images [58].

Fig. 8. Surface morphologies of X70 pipeline steel with different applied stresses in 3.5% NaCl solution after different durations at various hydrostatic pressures. (a) 0.1 MPa, no stress, t = 15 min, (b) 0.1 MPa, σ = 0.6σb, t = 200 h, (c) 5 MPa, σ = 0.6σb, t = 200 h, and (d) 10 MPa, σ= 0.6σb, t = 200 h. The units for the axes are micrometers (μm) [73].

Fig. 9. (a) High-resolution TEM images of Ti-6Al-4V after SSRT in 3.5% NaCl solution under 20 MPa, (b) electron diffraction pattern of δ hydrides in (a), and (c) schematic diagram of the higher hydrostatic pressure enhancing the hydrogen embrittlement of the titanium alloy [36].