Effect of copper addition on grain refinement of austenite in Fe-8wt.%Ni-(0.3)Wt.% Cu alloy

• Main Authors: Junaidi Syarif,, Zainuddin Sajuri,
• Format: Article
• Language: English
• Published: Universiti Kebangsaan Malaysia 2010
• Online Access: http://journalarticle.ukm.my/7445/1/26_Ayiesah.pdf; http://journalarticle.ukm.my/7445/; http://www.ukm.my/jsm/english_journals/vol39num6_2010/contentsVol39num6_2010.html

The effect of copper addition on martensitic structure and reversion from martensite to austenite behaviours upon heating were investigated to clarify mechanism of grain refinement of austenite in Fe-8wt.%Ni-Cu alloys. Upon water-quenching, the alloys underwent a martensitic transformation that exhibited a typical lath-martensitic structure. It was found that prior-austenite grain and martensite-packet sizes were refined with increasing copper content. The grain refinement was not due to a decrease of grain growth rate of the austenite. However, it was found that nucleation rate of the austenite on reversion was increased by the copper addition. In Fe-8wt.%Ni alloy heated in (austenite+ferrite) region, reversed austenite grains were formed at high angle boundaries such as prior austenite grain boundary and packet boundary. On the other hand, TEM observation of the Fe-8wt.%Ni-3wt.%Cu alloy revealed that fine copper particles precipitated within the martensitic structure and the reversed austenite grains also formed within lath-structures and lath boundary. It means that the copper addition promoted formation of the reversed austenite within martensitic matrix and resulted in the grain refinement of the prior-austenite in Fe-8wt.%Ni-Cu alloy.