Laser Powder Bed Fusion Processing of Fe-Mn-Al-Ni Shape Memory Alloy—On the Effect of Elevated Platform Temperatures

Felix Clemens Ewald,Florian Brenne,Philipp Krooß,Malte Vollmer,Thomas Niendorf,Tobias Gustmann

doi:10.3390/met11020185

Abstract

In order to overcome constraints related to crack formation during additive processing (laser powder bed fusion, L-BPF) of Fe-Mn-Al-Ni, the potential of high-temperature L-PBF processing was investigated in the present study. The effect of the process parameters on crack formation, grain structure, and phase distribution in the as-built condition, as well as in the course of cyclic heat treatment was examined by microstructural analysis. Optimized processing parameters were applied to fabricate cylindrical samples featuring a crack-free and columnar grained microstructure. In the course of cyclic heat treatment, abnormal grain growth (AGG) sets in, eventually promoting the evolution of a bamboo like microstructure. Testing under tensile load revealed a well-defined stress plateau and reversible strains of up to 4%.

Highlights

During the past decades, the development of new shape memory alloys (SMAs) gained a lot of interest in academia and the industry, in order to meet the demand for light and extremely compact actuators and damping devices
L-BPF processing of the Fe-34Mn-14Al-7.5Ni shape memory alloy at a build platform temperature of 500 ◦ C resulted in a crack-free microstructure in the as-built condition
It was stated that laser powder bed fusion (L-PBF) processing at 200 ◦ C leads to a strong increase of the hardness, resulting in an embrittlement of the microstructure

Summary

Introduction

The development of new shape memory alloys (SMAs) gained a lot of interest in academia and the industry, in order to meet the demand for light and extremely compact actuators and damping devices. It is well-known that binary Ni-Ti. SMAs suffer from poor cold workability, relatively high costs, as well as a narrow temperature window for practical application, limiting a more widespread industrial usage [1]. Based on these alloys it is possible to realize novel applications, e.g., in the construction sector [8].

Methods

Results

Conclusion