ASAXS STUDY OF THE COPPER ENRICHED PRECIPITATION IN THE 15-5PH-ALLOY

The 15-5 PH alloy (composed of Fe, Cr, Ni and Cu), aged at 450 and 500 -degrees-C has been mainly studied by anomalous small angle X-ray scat tering (ASAXS), as well as by transmission electron microscopy, X-ray microanalysis and Mossbauer spectrometry. The two phase model (practic ally pure Cu precipitates embedded in a Cu depleted matrix) accounts f or our results. From the ASAXS curves recorded at three absorption edg es (Cr, Cu and Fe), the partial structure functions PSF(ij) (with ij = Fe, (Cr+Ni) and Cu) have been determined. The DELTAC(Fe)/DELTAC(Cr+Ni ) and DELTAC(Fe)/DELTAC(Cu) ratios calculated at each and/or both edge s are in satisfactory agreement with those determined from X-ray micro analysis carried out on extraction replicas.