摘要
A Zr-1.15wt% Cr-0.10wt% Fe alloy was beta-quenched from 1050℃ to produce a supersaturated α′-phase, and then heated for varying times at temperatures from 650℃ to 760℃ to precipitate Zr(CrFe)_2.A thermoelectric power(TEP)technique and transmission electron microscopy(TEM)were used to monitor this precipitation process.Using the Johnson-Mehl-Avrami equation,the TEP results and a line regression method,the activation energy for diffusion and the diffusion coefficient of chromium(and Fe)in α-Zr have been calculated over 650℃～760℃.The temperature dependence of the diffusion coefficient,D_(Cr/α)(cm^2/s)is described at 650℃～760℃ by the relationship formula.The coarsening of the Zr(CrFe)_2 particles shows a t^(1/2)dependence of mean particle size on aging time,t.Such a time dependence is typical of coarsening where atom transfer across the interface is rate-controlling.
A Zr-1.15wt% Cr-0.10wt% Fe alloy was beta-quenched from 1050℃ to produce a supersaturated α′-phase, and then heated for varying times at temperatures from 650℃ to 760℃ to precipitate Zr(CrFe)_2.A thermoelectric power(TEP)technique and transmission electron microscopy(TEM)were used to monitor this precipitation process.Using the Johnson-Mehl-Avrami equation,the TEP results and a line regression method,the activation energy for diffusion and the diffusion coefficient of chromium(and Fe)in α-Zr have been calculated over 650℃～760℃.The temperature dependence of the diffusion coefficient,D_(Cr/α)(cm^2/s)is described at 650℃～760℃ by the relationship formula.The coarsening of the Zr(CrFe)_2 particles shows a t^(1/2)dependence of mean particle size on aging time,t.Such a time dependence is typical of coarsening where atom transfer across the interface is rate-controlling.
