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Effect of Heat Treatments on Microstructure of Rapidly Solidified TiCo Ribbons

Published online by Cambridge University Press:  26 February 2011

Kyosuke Yoshimi
Affiliation:
Institute for Materials Research, Tohoku University, Sendai, Miyagi 980–8577, JAPAN
Akira Yamauchi
Affiliation:
Institute for Materials Research, Tohoku University, Sendai, Miyagi 980–8577, JAPAN
Ryusuke Nakamura
Affiliation:
Institute for Materials Research, Tohoku University, Sendai, Miyagi 980–8577, JAPAN
Sadahiro Tsurekawa
Affiliation:
Department of Nanomechanics, Tohoku University, Sendai, Miyagi 980–8579, JAPAN
Shuji Hanada
Affiliation:
Institute for Materials Research, Tohoku University, Sendai, Miyagi 980–8577, JAPAN
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Abstract

The effect of heat treatments (aging or annealing) on microstructure was investigated for rapidly solidified ribbons of near-stoichiometric TiCo. In as-spun ribbons, it was observed by TEM that an equiaxed grain structure was developed and its crystal structure had been already B2-ordered, while a small amount of a second phase, Ti2Co, finely disperses in grains and along grain boundaries. Some grains were dislocation-free but others contained curved or helical dislocations and prismatic loops having a Burgers vector parallel to <100> directions. By annealing the as-spun ribbons at 700°C for 24h, the dislocation density was obviously increased compared with that of the as-spun ribbons, while grain growth appears to occur slightly. The increase of the dislocation density in the annealed ribbons is believed to result from the condensation and/or absorption of supersaturated vacancies. Therefore, the TEM observation results indicate that a large amount of supersaturated thermal vacancies were retained in the TiCo ribbons by the rapid solidification.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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References

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