Additive Manufacturing of NiTi Shape Memory Alloy for Biomedical Applications: Review of the LPBF Process Ecosystem

Abstract

NiTi shape memory alloys (SMAs) are used in a broad range of biomedical applications because of their unique properties including biocompatibility and high corrosion and wear resistance as well as functional properties such as superelasticity and the shape memory effect. The combination of SMAs and additive manufacturing can lead to revolutionary changes to the uses of SMAs in the biomedical industry. This article discusses the potential biomedical applications of NiTi that benefit from the AM process. We share the lessons learned in processing NiTi alloys with a focus on the laser powder bed fusion (LPBF) technique. The manufacturability, build quality, stable phases and transformation temperatures, microstructure, thermomechanical properties, microstructure tailoring, and functional properties of NiTi alloys produced via AM processing are reviewed. Current challenges such as expanding the process window, controlling the chemistry, and the performance and property responses are discussed, and potential opportunities including alloy design are discussed.

The role of NiTi shape memory alloys in quality of life improvement through medical advancements: A comprehensive review

“…This, alongside the complex thermal processes involved in AM, increases the difficulty in controlling the microstructure of the NiTi components. 113,115,116,[118][119][120]125 The fabrication method chosen for the manufacture of the component is dependent on many factors such as the area of use, property requirements of the product, production volume, production cost, material availability, availability of machinery, etc. In the biomedical sector, NiTi SMAs are more commonly used in the fabrication of surgical devices for endoscopic and laparoscopic surgery, orthopedics, medical implants, active catheters, stents, inferior vena cava filters, guidewires, stent grafts, prescription eyeglass frames, and much more.…”

Biomechanics of Additively Manufactured Metallic Scaffolds—A Review

“…SME and SE are created due to a reversible solid state Phase transformation between the two phases of Austenite and Martensite. These two interesting properties as well as biocompatibility, made Nitinol a great candidate for a wide range of biomedical applications [125]. Nitinol with SME has been used for developing compact actuator mechanisms in some biomedical devices such as Rectal Retractor [126].…”

“…Nitinol with SME has been used for developing compact actuator mechanisms in some biomedical devices such as Rectal Retractor [126]. Nitinol with SE properties has been used in several biomedical applications such as cardiovascular stents and artificial heart valves [125], bone implants [127,128], ankle foot orthosis (AFO) [129], and orthodontics arch wires [130].…”

“…Recently, additive manufacturing techniques, such as selective laser melting (SLM) has been investigated by different research groups for fabricating Nitinol with both SE and SME [131][132][133]. Additive manufacturing of Nitinol has the potential to introduce revolutionary and pioneering applications, such as stiffness-matched patent specific bone implants [125]. Jahadakbar, et al showed by introducing engineering porosity and lattice structures based on CT scan data to the bone implants, stiffness modulated porous NiTi implants can be fabricated via additive manufacturing [134][135][136].…”

Additive Manufacturing: An Opportunity for the Fabrication of Near-Net-Shape NiTi Implants

“…Furthermore, the homogeneity and purity of the AM-fabricated component are important factors for preserving its biocompatibility. The surface finish and accuracy of the produced biomaterial, as well as the final costs of the product, should also be taken into account [99][100][101]. Considering the superelasticity of shape-memory alloys, particularly NiTi with an approximately equal content of Ni and Ti, the focus of their practical development has been on establishing and selecting the optimum AM approach from the viewpoint of controlling the porosity and mechanical behavior.…”