抄録
Cast duplex stainless steel of CF3M was aged at 450°C for up to 10000 h. The ferritic phase was hardened and embrittled by the ageing. Cyclic polarization curves were measured in 0.5 kmol/m3 H2SO4+0.01kmol⁄m^3KSCNsolutiontoinvestigatetheelectrochemicalbehaviourduringphasedecompositionoftheferriticphase.Inaddition,the3−Dmicrochemicalchangewasexaminedbyarecentlybuiltpositionsensitiveatomprobe(POSAP).Thereactivationcurrentpeakappearsinthecyclicpolarizationmeasurementafter400hageing.Thisresultsfromthedissolutionofthechromium−depletediron−richregionformedduringdecompositionoftheferriticphase.
ThePOSAPanalysisofthe10000hagedsteelshowsawell−developedphasedecompositionintothechromium−richandiron−richregionsinseveralnanometerscale.Flatplate−likechromium−richregions(Cr≥50at%)ofafewnanometerthicknessareobservedataspacingofafewnanometer,whiletheiron−richregions(Cr<12at%)formthepercolatedstructuresurroundingtheflatplate−likechromium−richregions.
