Acta Metallurgica Sinica (English Letters) ›› 2016, Vol. 29 ›› Issue (3): 282-286.DOI: 10.1007/s40195-016-0386-1

• Orginal Article • Previous Articles     Next Articles

Shape Memory Behavior of [111]-Oriented NiTi Single Crystals After Stress-Assisted Aging

Irfan Kaya1(), Hirobumi Tobe2, Haluk Ersin Karaca2, Emre Acar3, Yuriy Chumlyakov4   

  1. 1 Department of Mechanical Engineering, Faculty of Engineering, Anadolu University, 26555 Eskisehir, Turkey
    2 Department of Mechanical Engineering, University of Kentucky, Lexington, KY 40506, USA
    3 Department of Aircraft Engineering, Erciyes University,38039 Kayseri, Turkey
    4 Siberian Physical-Technical Institute at Tomsk State University, Tomsk 634050, Russia
  • Received:2015-11-02 Revised:2015-12-15 Online:2016-02-26 Published:2016-03-20

Abstract:

The shape memory behavior of [111]-oriented Ni51Ti49 (at.%) single crystals was investigated after stress-assisted aging at 500 °C for 1.5 h under a compressive stress of -150 MPa. It was found that a single family of Ni4Ti3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress. Stress-assisted aging resulted in tensile two-way shape memory effect strain of 1.56% under -5 MPa. Thermal cycling under -600 MPa resulted in a transformation strain of -2.15%, while the subsequent thermal cycling under -5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.

Key words: Shape memory alloy (SMA), Two-way shape memory effect, Aging treatment, Precipitation, Phase transformations