EXPERIMENTAL-STUDY ON DIFFUSION-INDUCED RECRYSTALLIZATION IN CU FE/CUDIFFUSION COUPLES USING CU SINGLE-CRYSTALS/

Diffusion induced recrystallization (DIR) in a face-centered-cubic (f. c.c.) Fe phase was experimentally studied in the Fe(Cu) system. The no tation Fe(Cu) means that Cu atoms diffuse into a pure Fe or binary Fe- Cu phase. The Cu/Fe/Cu and Cu/(Fe-4.8Cu)/Cu diffusion couples consisti ng of a polycrystalline Fe phase specimen and pure Cu Single crystals with the same crystallographic orientation were annealed at 1 193 and 1 323 K far various times between 3.0 x 10(2) and 8.6 x 10(4) s. The p enetration of Cu in the f.c.c. Fe phase was found to occur at rates 10 0 times greater than the one evaluated from the volume diffusion. This unusually vapid penetrations due to DIR, which takes place in the Fe phase from the interfaces of the diffusion couples. DIR was observed t o occur only in the Cu/(Fe-4.8Cu)/Cu diffusion couples annealed at 1 3 23 K under the present experimental conditions. The thickness w of the Fe phase decreases with increasing annealing time t according to the equation w/w(0)=1-7.09 x 10(-8)(root t/w(0)), whereas the thickness l of the DIR region increases with increasing annealing time according t o the equation l=1.58 x 10(-6)(root t/t(0))(0.29). Here, w(0) is the i nitial thickness of the Fe phase, and t(0) is unit time, 1 s. The thic knesses w, w(0) and l are measured in mr and the annealing time t is m easured in s.