A Novel Fabrication Method for Nitinol Shape Memory Alloys

Abstract

Nitinol (NiTi) shape memory alloys are widely used in a variety of biomedical applications, such as dental implants, cervical and lumbar vertebral replacements, joint replacements and stents. In this study, commercially pure Ti and Ni foils ~100 um thick were diffusion bonded in vacuum. The experimental conditions were optimized to achieve a near equiatomic composition to produce NiTi SMA thin foil of approx. 5-8 micron thick. The cross-sectional surfaces of joint were subjected to metallographic investigation using optical microscope after grinding, polishing and etching. Scanning electron microscope equipped with EDX system was utilized to characterize the bonded layer and compositional analysis. Differential scanning calorimetry (DSC) technique was employed to determine the shape memory effect. The samples were subjected to X-ray diffraction analysis in order to establish phase structures formed during the diffusion bonding stage. An ultra fast femto-second laser facility was utilized to ensure the production of complex shapes or patterns within micron scale.

Advances in Selective Laser Melting of Nitinol Shape Memory Alloy Part Production

“…Powder shape and particle size distribution are also found to affect the microstructure [ 69 , 70 ]. Laser processing often changes the microstructures and phases of the feedstock alloy powder.…”

Seismic Response Control Using Shape Memory Alloys: A Review

“…Roh and Reinhorn (2010) proposed the use of SMA bars to improve hysteretic performance of the precast segmental bridge piers and insure self-centering capacity to the post-tensioned (PT) column system. They developed a new analytical model for SMA bars and numerically examined the performance of the PT segmental columns with superelastic SMA bars.…”

Properties of NiTi Shape Memory Alloy Micro-Foils Obtained by Pulsed-Current Sintering of Ni/Ti Foils

“…After that, heat treatment is required to obtain desirable properties [21]. A hot pressing technique was shown to be very effective for obtaining nickel/titanium plates and multilayers of thin films for diffusion bonding purposes [22,23], powder metallurgy [24], and micro-foil/laminate preparation [21,[25][26][27][28]. The positive influence of the application of electrical current during synthesis on the NiTi phase creation was reported in [26,27,29].…”