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Phase formation upon crystallization of the melt-spun high temperature shape memory alloys along ZrCu-Zr2CuNi quasibinary cross-section
|Georgiy S. Firstov 1, Yuri Koval 1, Philippe Vermaut 2, Richard Portier 2, Patrick Ochin 3, Jan Van Humbeeck 4|
1. G. V. Kurdyumov Institute for Metal Physics of the National Academy of Sciences (IMP), Vernadsky Blvd. 36, Kiev UA03680, Ukraine
It is known that Ni replacement of Cu in ZrCu high temperature shape memory alloy (HTSMA) results in the increase of the temperatures of the martensitic transformation (MT) . Once the Ni content reaches 20 at.%, the temperatures of MT are becoming higher than the temperature of crystallization of the amorphous alloy with the same composition  and crystallization from the amorphous state in this case takes place through formation of B19` phase without any visible signs of the nanoscale phase separation.
Transmission electron microscopy (TEM) in the present study revealed that once the Ni content is not sufficient to increase the MT temperatures above crystallization one, the nanoscale phase separation plays important role. The increase of MT above crystallization like in , indeed, results in the preferential formation of B19` upon crystallization. DSC and X-ray diffraction were used to find a correspondence between kinetics of the crystallization and structural phase formation qualitatively detected by TEM.
 Koval Yu.N., Firstov G.S., Delaey L., Van Humbeeck J., Scr. Met. et Mat., v.31, No. 7, 1994, pp.799-802.
 Firstov G.S., Koval Yu.N., Van Humbeeck J., Portier R., Vermaut P., Ochin P., Materials Science and Engineering: A, Volumes 438-440, 25 November 2006, Pages 816-820
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium E, by Georgiy S. Firstov
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-11 15:40 Revised: 2009-06-07 00:44