Laser powder bed fusion of a Fe–Mn–Si shape memory alloy

3D and 4D Printing of Complex Structures of FeMnSi‐Based Shape Memory Alloy Using Laser Powder Bed Fusion

“…To investigate the shape recovery and tensile mechanical properties of 3D‐printed Fe‐SMAs, simple rectangular blocks were fabricated via L‐PBF, as shown in Figure a, using a commercial L‐PBF machine (Sodick OPM 250L, Japan) with a laser power of 420 W. Here, we used the pre‐alloyed Fe‐SMA powder that had been used in our previous work. [ 18 ] Moreover, L‐PBF conditions (e.g., laser scanning speed) were carefully adjusted to avoid any microstructural defects such as cracks and pores. The microstructures of the as‐fabricated Fe‐SMAs consisted of both brittle bcc‐δ and ductile fcc‐γ phases.…”

“…[12][13][14] Unlike SMPs, SMAs show not only the SME but also the so-called pseudo-elasticity (PE) functionality, through which an applied deformation is immediately reversed while unloading without any temperature change. Through conventional metallurgical processes other than 3D printing, such as casting, forming, or powder sintering, NiTi-based SMAs, [15,16] Cu-based SMAs, [17] and Fe-based SMAs (Fe-SMAs) [18] have been extensively developed. Among them, NiTi-based SMAs are the most widely used alloys for 3D printing because they induce the SME and PE as well as exhibit good bio-compatibility.…”

“…[9] The slight difference in the tensile behavior due to the vertical and horizontal directions may have originated from the strong crystallographic texture of the Fe-SMA produced through L-PBF. [18,28] Figure 1c shows the recovery ratios for PE and shape recoveries (i.e., the ratio of the bending strain for PE and shape recovery to the applied bending strain) for the Fe-SMA strips fabricated in the two directions. The samples were bent with a bending strain of 5.26%, unloaded, and heated to 200 °C.…”

“…[12,13] Very recently, we successfully fabricated a Fe-17Mn-5Si-10Cr-4Ni (wt.%) alloy via L-PBF for the first time, which showed a strong SME and high mechanical strength even though the alloy did not contain any carbide forming element for enhancing the SME by the fine precipitations. [18] The main motivation of this work is to apply the L-PBF process to produce complex 3D structures of the Fe-SMA for fabricating novel functional structures. For this purpose, various functional 3D structures of the Fe-SMA were 3D printed to demonstrate the possibility of fabricating complex 3D structures of the Fe-SMA near-freely by the L-PBF, which can open new possibilities in the manufacturing of novel functional structures such as metamaterial structures, artificial muscles, self-healing devices, and 4D-printed structures.…”

“…[ 12,13 ] Very recently, we successfully fabricated a Fe‐17Mn‐5Si‐10Cr‐4Ni (wt.%) alloy via L‐PBF for the first time, which showed a strong SME and high mechanical strength even though the alloy did not contain any carbide forming element for enhancing the SME by the fine precipitations. [ 18 ]…”