Dissimilar Laser Welding of a NiTi Shape Memory Alloy to Ti2AlNb

Fuguo Ge,Wenchao Ke,João Pedro Oliveira,Fissha Biruke Teshome,Yongmei Li,Bei Peng,Zhi Zeng

doi:10.3390/met11101578

Fuguo Ge, Wenchao Ke + Show 5 more

Open Access

https://doi.org/10.3390/met11101578

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Abstract

NiTi-based shape memory alloys and the Ti2AlNb alloy have gained increasing importance in the aerospace field. The joining of these two materials can further increment the importance and usage of these relevant engineering materials and expand their potential applications. However, when joining NiTi-based shape memory alloys to Ti-based alloys, the formation of brittle Ti-rich intermetallic compounds often occurs, significantly limiting their functionality and use. Dissimilar joints between a NiTi shape memory alloy and Ti2AlNb alloy were obtained using a 0.1 mm thick Niobium (Nb) interlayer via laser welding. By process optimization, sound joints were obtained. The microstructure evolution was assessed by means of electron microscopy, whereas the mechanical strength of the joints was evaluated using lap shear tensile testing. The best performing joints were seen to fracture at maximum loads above 1230 N, thus allowing us to consider this dissimilar pair for structural applications.

Highlights

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Due to their unique properties of superelasticity (SE) and shape memory effect (SME), NiTi shape memory alloys are involved in a wide range of applications, including aerospace, biomedicine, energy development, and machinery, as well as other fields [1,2,3]
There is a lack of systematic and in-depth research on the relationship between process parameters, microstructure evolution, and joint performance when it comes to dissimilar welding of Ti2AlNb to NiTi-based alloys
Metals 2021, 11, 1578 of the weld was not contaminated by oxygen or nitrogen

Summary

Introduction

Due to their unique properties of superelasticity (SE) and shape memory effect (SME), NiTi shape memory alloys are involved in a wide range of applications, including aerospace, biomedicine, energy development, and machinery, as well as other fields [1,2,3]. Laser welding has been widely used as an effective joining method for creating dissimilar joints as it possesses key advantages such as high energy density, reduced extension of the thermally affected regions, and low residual stresses [27,28]. There is a lack of systematic and in-depth research on the relationship between process parameters, microstructure evolution, and joint performance when it comes to dissimilar welding of Ti2AlNb to NiTi-based alloys. We bridge this gap in this work by joining for the first time a NiTi shape memory alloy to the Ti2AlNb alloy. This work is of great significance for applying complex components composed of dissimilar joints made of Ti2AlNb and NiTi

Materials and Methods

Results

Fracture Characteristics of Lap Joint