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

Abstract

The shape memory behavior of [111]-oriented Ni51Ti49 (at.%) single crystals was investigated after stress assisted aging at 500 degrees 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%.