Research on Formation Process of Nano-chromium Phase in Centrifugal Casting Cu-Cr-Zr-Mg Alloy
A Cu-0.43Cr-0.22Zr-0.092Mg(wt%)alloy which has a large amount of elemental chromium phases with 2.5-5 nm particles and 0.6-1.2 nm spacing striped shape in the solidified structure was prepared by vacuum melting+centrifugal casting technology.Aiming at the problem that the reason for the formation of nano-scale elemental chromium phase is not clear,the as-cast microstructure of the alloy was observed and analyzed by means of SEM,XRD,TEM and HRTEM(high-resolution TEM),the critical crystal nucleus radius of chromium phase was calculated,and the nucleation and growth process of elemental chromium phase was studied.The results show that under the centrifugal force,the Cu-0.43Cr-0.22Zr-0.092Mg(wt%)alloy melt first produces chromium segregation,which creates conditions for chromium phase nucleation.After the chromium phase nucleation,under the action of centrifugal force,the chromium phase crystal nucleus grows slightly when moving to the chromium-poor region,and basically stops growing after entering the chromium-poor region,and finally several nano-sized elemental chromium phases are obtained.
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