Microstructure evolution of heat treated NiTi alloys

27th Joint Seminar Development of Materials Science in Research and Education

材料科学;教育

Losertová, M.^1 ; Štencek, M.^1 ; Matýsek, D.^2 ; Štefek, O.^1 ; Drápala, J.^1

VŠB - Technical University of Ostrava, Faculty of Metallurgy and Materials Engineering, 17. listopadu 15, Ostrava-Poruba

708 33, Czech Republic^1

VŠB - Technical University of Ostrava, Faculty of Mining and Geology, 17. listopadu 15, Ostrava-Poruba

708 33, Czech Republic^2

关键词: ageing;    Micro-structure evolutions;    Microhardness measurement;    Microstructural changes;    Ni4Ti3;    NiTi;    Thermomechanical properties;    Transformation temperatures;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/266/1/012008/pdf
DOI  :  10.1088/1757-899X/266/1/012008

来源: IOP

【 摘 要 】

Superelastic behavior of off-stoichiometric NiTi alloys is significantly affected by microstructure changes due to heat treatment. Applying appropriate thermal treatments important effects on microstructural changes, transformation temperatures and thermomechanical properties of final NiTi products can be achieved. The experimental samples of NiTi alloy with 55.8 wt.% Ni were submitted to heat treatment and the microstructures before and after the treatment were observed. The thermal regimes consisted of annealing treatment at 600 °C for 1 hour followed by water quenching and of ageing at eight different temperatures (250, 270, 290, 300, 350, 400, 450 and 500 °C) for 30 minutes. Microstructure features studied by means of optical and scanning electron microscopies, EDX microanalyses, X-ray diffraction analyses and microhardness measurement, have shown that higher ageing temperatures led to microstructure changes and corresponding increase in microhardness.