Corrosion And Abrasion Behaviors Of AZ31 Magnesium Alloy Irradiated By HIPIB

The surface modification of AZ31 alloys has been investigated by High-intensity pulsedion beam (HIPIB), which is performed in TEMP-6 type HIPIB apparatus with ion currentdensity of 100 A/cm² and shot numbers from 1 to 10. For AZ31 alloys unirradiated andirradiated by HIPIB, the phase microstructure and surface morphology are characterized byX-ray diffraction (XRD) and scanning electron microscopy (SEM); the electrochemicalcorrosion behaviors are evalued by using anodic polarization measurements and electrochemicalimpedance spectroscopy (EIS); the abrasion behaviors are studied by surface profile apparatusand micro-hardness tester as well as abrasive wear tester. The results indicate that:Theβ-Mg₁₇Al₁₂ phase is precipitated and the size ofα-Mg phase is fined and thesurface is glazed and worn tracks are disappeared, and ablation craters as well assedimentation particles are formed on the surface after irradiation by HIPIB.Anodic polarization curves of AZ31 alloys in 0.01 and 0.1 mol/L NaCl solutions withpH12 show typical self-passivation. All self-corrosion potential Ecorr and pitting potential E_ptof AZ31 alloys irradiated from 1 shot to 10 shots by HIPIB are more positive than thatunirradiated, especially for 5 shots which have broader passive regions. The E_corr and E_pt ofAZ31 alloy irradiated for 5 shots are increased by some 560 mV and 630 mV in 0.01 mol/LNaCl solution, 350 mV and 420 mV in 0.1 mol/L NaCl solution, respectively. And thisindicates that the general corrosion resistance and pitting corrosion resistance have beenpronounced improved. The E-t curves and EIS indicate that AZ31 alloys unirradiated, whichis immersed in 0.1 and 0.5 mol/L NaCl solution with pH12, proceed a general corrostion, butthat irradiated for 5 shots by HIPIB show firstly produce a passivation film, and the ability ofself-passivation have been improved. The EIS of AZ31 alloys irradiated for 5 shots by HIPIBboth show a capacitive arc in HF and an inductive arc in LF in 0.1 and 0.5 mol/L NaClsolutions with pH12. And the diameters of the two capacitive arcs are equivalent, but whencompared with unirradiated AZ31 alloys, the values of diameters decrease by more than 2 and1 orders, respectively. This indicated that under the condition of localized corrosion, thecharacteristics of EIS mainly are dependent on the electrochemical behaviors of hole nucleusin a broad range of frequency.For 5shots, the micro-hardness of AZ31 alloys irradiated is improved from 645 MPa to875 MPa, the average friction coefficient decreases from 0.38 to 0.35, and the worn deepdecreases from 8.0μm to 4.0μm. This indicate the abrasion resistance have been improved.