The influence of Cu addition on precipitation in Fe-Cr-Ni-Al-(Cu) model alloys.
Precipitation in Fe-Cr-Ni-Al-(Cu) model alloys was investigated after ageing for 0.25, 3, 10 and 100h at 798K. Characterization of nanoscale precipitates was performed using three-dimensional atom probe microscopy and transmission electron microscopy. The precipitates are found to be enriched in Ni and Al (Cu) and depleted in Fe and Cr. After 0.25h of ageing the number density of precipitates is approximately 8x10(24)m((-3)), their volume fraction is about 15.5% and they are near-spherical with an average diameter of about 2-3nm. During further ageing the precipitates in the both alloys grow, but the coarsening behaviour is different for both alloys. The precipitates of the Cu-free alloy grow much faster compared with the Cu-containing alloy and their density decreases. Precipitates in Cu-free alloy change to plate shaped even after 10h of ageing, whereas those of Cu-containing alloy remain spherical up to 10h of ageing. The influence of Cu addition on precipitation in these model alloys is discussed with respect to the different coarsening mechanisms.
Höring
S
S
Helmholtz Centre Berlin for Materials and Energy, Glienicker Str. 100, SF3, 14109 Berlin, Germany. hoering@helmholtz-berlin.de
Wanderka
N
N
Banhart
J
J