High resolution transmission electron microscopy study on the nano-scale twining of θ-NiMn precipitates in Fe-Ni-Mn maraging alloy

Syamak Hossein Nedjad 2Mahmoud Nili Ahmadabadi 3Tadashi Furuhara 1Tadashi Maki 1

1. Kyoto University, Kyoto 606-8501, Japan
2. Sahand University of technology (SUT), Sahand New Town, Tabriz, Iran, Tabriz 51335-1996, Iran
3. University of Tehran (UT), North-Kargar, Tehran 14395-731, Iran

Abstract

Precipitation of nanometer-sized f.c.t. θ-NiMn intermetallic compounds was found to cause age hardening in a Fe-10Ni-7Mn (wt. %) maraging alloy during isothermal aging at 773 K. Conventional and high resolution transmission electron microscopy (TEM) was used to study microstructural characteristics of the f.c.t. θ-NiMn precipitates. Bright-field TEM images showed twinning of both fine matrix and coarse grain boundary precipitates. High resolution lattice imaging of the precipitates illustrated a nano-scale twinning of the precipitates. An atomistic model, corresponding to the lattice images, was developed for twinning reaction indicating the {111} and <111> as twin planes and directions, respectively.

Keywords: Maraging: Precipitation: NiMn: Twin

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by Syamak Hossein Nedjad
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-31 13:54
Revised:   2009-06-07 00:44