Structure, Martensitic Transformation, and Damping Properties of Functionally Graded NiTi Shape Memory Alloys Fabricated by Laser Powder Bed Fusion

Abstract

Besides the unique shape memory effect and superelasticity, NiTi alloys also show excellent damping properties. However, the high damping effect is highly temperature-dependent, and only exists during cooling or heating over the temperature range where martensitic transformation occurs. As a result, expanding the temperature range of martensite transformation is an effective approach to widen the working temperature window with high damping performance. In this work, layer-structured functionally graded NiTi alloys were produced by laser powder bed fusion (L-PBF) alternating two or three sets of process parameters. The transformation behavior shows that austenite transforms gradually into martensite over a wide temperature range during cooling, and multiple transformation peaks are observed. A microstructure composed of alternating layers of B2/B19′ phases is obtained at room temperature. The functionally graded sample shows high damping performance over a wide temperature range of up to 70 K, which originates from the gradual formation of the martensite phase during cooling. This work proves the potential of L-PBF to create NiTi alloys with high damping properties over a wide temperature range for damping applications.

3D printing metal implants in orthopedic surgery: Methods, applications and future prospects

“…This protective membrane prevents the toxic and allergenic effects of Ni release, so we wanted to increase the formation and thickness of TiO2 [ 119 ]. Typically, SLM methods are commonly used to print SMA [ 120 , 121 ]. Intervertebral fusion devices are one of the recently identified applications for porous Ni–Ti in spine surgery, with one commercial product commercially available since 2002 under the trade-name Actipore (from Biorthex, Canada) for lumbar and cervical interbody devices [ 122 ].…”

Effects of the Energy Density on Pores, Hardness, Surface Roughness, and Tensile Characteristics of Deposited ASTM 316L Specimens with Powder-Bed Fusion Process

“…Powder bed fusion (PBF) is a typical metal AM process. The PBF process uses spherical metallic powder material [ 1 , 4 , 5 , 6 ]. The desired solid part is fabricated by repeating several sequences, such as powder feeding, melting of the fed powder layer, and solidification of the melted powder [ 5 , 6 , 7 ].…”

“…The PBF process uses spherical metallic powder material [ 1 , 4 , 5 , 6 ]. The desired solid part is fabricated by repeating several sequences, such as powder feeding, melting of the fed powder layer, and solidification of the melted powder [ 5 , 6 , 7 ]. During the deposition process, a high-density energy source is used to melt powder materials, such as laser and electron beams.…”

“…During the deposition process, a high-density energy source is used to melt powder materials, such as laser and electron beams. The PBF process can be classified into selective laser melting (SLM), selective laser sintering (SLS), direct metal laser sintering (DMLS), electron beam melting (EBM), and electron beam sintering (EBS), depending on the type of energy source and material fusion characteristics [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The PBF process has various process parameters, including laser power, scanning speed, layer thickness, beam diameter, hatching distance, hatching angle, ambient temperature, and temperature of the building plate [ 9 , 10 , 11 , 12 ].…”