J Mater Sci Technol ›› 1994, Vol. 10 ›› Issue (2): 139-142.

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TEM Investigations of Thermal Stability of Nanocrystamne Co_(81)Cr_(19)

Jingtang WANG; Bingzhe DING; Huayu TONG and Qihong SONG (State Key Lab of RSA, Institute of Metal Research, Academia Sinica, Shenyang, 110015, China)(To whom correspondence should be addressed)   

  • Received:1994-03-28 Revised:1994-03-28 Online:1994-03-28 Published:2009-10-10

Abstract: In situ transrnission electron microscopic observations were carried out to study the thermal stability of nanocrystalline Co81 Cr19 (n-Co81 Cr19) alloy prepared by d.c. sputtering, The TEM results show that the originally existed nanocrystalline phase hcp-CoCr is thermally stable, no apparent grain growth was observed until annealing to the final stage at.800℃. But the evolution of .microstructure of amorphous oxide Co2Cro4. which is formed duting in situ annealing. is drastically affected by the electron irradiation. In the electron irradiated area. the newly formed amorphous oxide Co2CrO4crystallizes at about 550℃. and grows into fine crystals finally. However, in the electron nonirradiated area, the amorphous oxide Co2CrO4 crystallizes at about 630℃. and grows into large strip shaped crystals during afterward annealing. the space between strip shaped crystals are also fine grained hcp-CoCr alloy. XRD analysis result of the thick film Co81 Cr19 is in good agreement with that of in situ TEM for the excellent stability of hcp-CoCr