Microstructure changes in two phase β+γ Co-Ni-Al ferromagnetic shape memory alloys in relation to Al/Co ratio
|Wojciech Maziarz 1, Jan M. Dutkiewicz 1, Ruben Santamarta 2, Eduard Cesari 2|
1. Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland
The microstructure of annealed at 1200°C and water quenched Co35+x-Ni40-x-Al25 (x = 0, 2.5, 5.0) ferromagnetic shape memory alloys has been investigated by optical (OM) and analytical transmission electron microscopy (TEM). The deformed microstructure consisted of elongated grains of martensite and γ phases as observed using polarized OM and Nomarski contrast. The annealing twins were found frequently in the γ phase. The volume fraction of γ phase has been determined using quantitative image analysis method. TEM observations raveled frequent stacking faults within martensite and its teragonality as well as dissociated dislocations within γ phase. The crystallographic relationship between martensite and γ grains has been determined basing on electron diffraction patterns. The elemental mapping technique and chemical point analyses allowed to determine the composition of particulate phases. The measured Al/Co ratio in the β phase of quenched alloys has been shown to be related to Ms temperature.
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium E, by Wojciech Maziarz
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 14:33 Revised: 2009-06-07 00:44