EFFECT OF β-QUENCHING ON THE CORROSION RESISTANCE OF Zr-4 ALLOY IN LiOH AQUEOUS SOLUTION

To investigate the effect of beta-quenching on the corrosion behavior, Zr-4 specimens were beta-quenched and subsequently annealed at 480-600 degrees C for 2-200 h. The, corrosion tests were carried out in 0.01 mol/L LiOH aqueous solution at 360 degrees C/18.6 MPa. The microstructure of Zr-4 specimens and fracture surface morphology of oxide films on the corroded specimens were observed by TEM and HRSEM, respectively. The results show that Zr-4 specimens exhibit excellent corrosion resistance as Zr-Sn-Nb alloys in LiOH aqueous solution after increasing the solid solution content of Fe and Cr in alpha-Zr matrix by suitable quenching rate from beta-phase to avoid the formation of beta-Zr. When the cooling rate is too fast, the specimens show worse corrosion resistance due to the formation of beta-Zr. After annealing at 480-600 degrees C, the better corrosion resistance of Zr-4 specimens can be obtained with increasing annealing temperture and time due to the decomposition of beta-Zr.