Nanostructural evolution of Cr-rich precipitates in a Cu-Cr-Zr alloy during heat treatment studied by 3 dimensional atom probe

Nanostructural evolution of Cr (Cr-rich) precipitates in a Cu-0.78%Cr-0.13%Zr alloy has been studied after aging and overaging (reaging) by laser assisted local electrode 3 dimensional atom probe (Laser-LEAP). This material is a candidate for the first wall and divertor components of future fusion reactors. After prime aging at 460 degrees C, Cr precipitates enriched with Zr were observed. Further reaging at 600 degrees C caused the precipitates to grow to almost spherical Cr precipitates with 5 nm (1 h) in diameter and plate-like ones with 20 nm (4 h), respectively. Zr and impurities of Si and Fe were concentrated around the Cr precipitates, resulting in an almost pure Cr cores with interface regions enriched with Zr and the impurities. Probably, the strain induced by the incoherency of BCC Cr with matrix FCC Cu is relaxed by the formation of the enriched regions.