Characteristics of the stress-induced formation of R-phase in ultrafine-grained NiTi shape memory wire

JOURNAL OF ALLOYS AND COMPOUNDS

卷:579

Article

Olbricht, J.^1,2  Yawny, A.^3,4  Pelegrina, J. L.^3,4  Eggeler, G.¹  Yardley, V. A.¹ 

[1] Ruhr Univ Bochum, Inst Mat, D-44780 Bochum, Germany

[2] BAM Fed Inst Mat Res & Testing, D-12200 Berlin, Germany

[3] Ctr Atom Bariloche, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina

[4] Consejo Nacl Invest Cient & Tecn, RA-1033 Buenos Aires, DF, Argentina

关键词: NiTi shape memory alloys;    Pseudoelasticity;    Stress-induced phase transformations;    Localization;    R-phase;   

DOI  :  10.1016/j.jallcom.2013.06.056

来源: Elsevier

【 摘 要 】

The transformation between the cubic B2 and monoclinic B19' phases in ultrafine-grained pseudoelastic NiTi can occur as a two-step process involving the intermediate rhombohedral R-phase. Experimental work using differential scanning calorimetry, electrical resistance measurements and transmission electron microscopy has demonstrated the formation of this intermediate phase during thermal cycling and during mechanical loading. In the present paper, complementary mechanical and thermographic results are presented which allow to further assess the character of the stress-induced R-phase formation. The transformation from B2 to R-phase is demonstrated to occur homogeneously within the gauge length rather than via advancing Luders-type transition regions as it is the case in the localized transformation from B2 or R-phase to B19'. (C) 2013 Elsevier B.V. All rights reserved.

【 授权许可】

Free