Spatial characteristics of nickel-titanium shape memory alloy fabricated by continuous directed energy deposition

TL;DR

This paper introduces a continuous directed energy deposition method for fabricating nickel-titanium shape memory alloys, resulting in improved microstructure uniformity and enhanced mechanical properties compared to traditional layer-by-layer additive manufacturing.

Contribution

The study presents a novel continuous energy deposition technique that achieves more uniform microstructures and better mechanical performance in NiTi shape memory alloys.

Findings

Monotonic temperature history during fabrication

Uniform phase distribution and microstructure morphology

High compressive strength and strain in fabricated specimens

Abstract

Additive manufacturing has been adopted to process nickel-titanium shape memory alloys due to its advantages of flexibility and minimal defects. The current layer-by-layer method is accompanied by a complex temperature history, which is not beneficial to the final characteristics of shape memory alloys. In this study, a continuous directed energy deposition method has been proposed to improve microstructure uniformity. The spatial characterization of nickel-titanium shape memory alloy fabricated by continuous directed energy deposition is investigated to study the temperature history, phase constituent, microstructure, and mechanical properties. The results indicate that the fabricated specimen has a monotonic temperature history, relatively uniform phase distribution and microstructure morphology, as well as high compressive strength (2982 MPa~3105 MPa) and strain (37.7%~41.1%). The reported method is expected to lay the foundation for spatial control during the printing of functional structures.