Multiple-step martensitic transformations in Ni-rich NiTi alloys -: an in-situ transmission electron microscopy investigation

被引:128
作者
Dlouhy, A
Khalil-Allafi, J
Eggeler, G
机构
[1] Ruhr Univ Bochum, Inst Werkstoffe, D-44780 Bochum, Germany
[2] Acad Sci Czech Republ, Inst Phys Mat, CZ-61662 Brno, Czech Republic
关键词
D O I
10.1080/0141861021000034531
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Multiple-step martensitic transformations in Ni-rich NiTi shape memory alloys have so far been rationalized on the basis of dislocation stress fields, coherency stress fields around Ni4Ti3 precipitates and evolving Ni concentrations between precipitates during ageing. The primary objective of the present paper is to show that such transformations can also occur owing to heterogeneous microstructures that form during ageing of solution annealed defect-free materials. These microstructures are characterized by Ni4Ti3 grain-boundary precipitation and by precipitate-free grain interiors. Two microstructures which give rise to two and three distinct differential scanning calorimetry (DSC) peaks on cooling from the B2 regime are subjected to in-situ cooling and heating cycles in the transmission electron microscope. Martensitic transformations are directly studied and the observations provide a new explanation for multiple-step martensitic transformations in Ni-rich NiTi alloys. Most importantly the results of the present study allow us to understand why DSC chart features on cooling from the B2 regime change during ageing, where they lose their one-step character (after solution annealing at 1123 K for 900 s) and evolve from two-step (after ageing at 773 K for 3.6 ks) to three-step (after ageing at 773 for 36 ks K) transformations.
引用
收藏
页码:339 / 363
页数:25
相关论文
共 36 条
[1]   The mechanism of multistage martensitic transformations in aged Ni-rich NiTi shape memory alloys [J].
Allafi, JK ;
Ren, X ;
Eggeler, G .
ACTA MATERIALIA, 2002, 50 (04) :793-803
[2]  
Bataillard L, 1998, PHILOS MAG A, V78, P327, DOI 10.1080/01418619808241907
[3]   ESTIMATE OF FOIL THICKNESS BY STEREOMICROSCOPY TECHNIQUE [J].
DLOUHY, A ;
PESICKA, J .
CZECHOSLOVAK JOURNAL OF PHYSICS, 1990, 40 (05) :539-&
[4]  
DLOUHY A, 1996, PRAKT METALLOGR-PR M, V33, P1
[5]   An overview of nitinol medical applications [J].
Duerig, T ;
Pelton, A ;
Stöckel, D .
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 1999, 273 :149-160
[6]   Creep behavior of NiTi shape memory alloys and the effect of pre-creep on the martensitic phase transformation [J].
Eggeler, GF ;
Neuking, K ;
Dlouhy, A ;
Kobus, E .
SHAPE MEMORY MATERIALS, 2000, 327-3 :183-186
[7]   On precipitation kinetics in TiNi shape memory alloys [J].
Filip, P ;
Mazanec, K .
SCRIPTA MATERIALIA, 2001, 45 (06) :701-707
[8]   The influence of aging on critical transformation stress levels and martensite start temperatures in NiTi: Part I - Aged microstructure and micro-mechanical modeling [J].
Gall, K ;
Sehitoglu, H ;
Chumlyakov, YI ;
Kireeva, IV ;
Maier, HJ .
JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME, 1999, 121 (01) :19-27
[9]   THE B2 TO R TRANSFORMATION IN TI50NI47FE3 AND TI49.5NI50.5 ALLOYS [J].
GOO, E ;
SINCLAIR, R .
ACTA METALLURGICA, 1985, 33 (09) :1717-1723
[10]   Structural study of the R-phase in Ti-Ni alloy by the rietveld method [J].
Hara, T ;
Ohba, T ;
Otsuka, K .
JOURNAL DE PHYSIQUE IV, 1995, 5 (C8) :641-645