Guest Editorial for Energy-Assisted Additive Manufacturing and 4D Printing

Abstract

For this special section on “Energy-assisted additive manufacturing (AM) and 4D printing,” we are glad to finally accept ten papers across different AM topics. I would like to thank editors Dr. Sandra Kalveram and Dr. Shaoying Cui from the Advanced Engineering Materials journal for their help in organizing and publishing this special section. I would like to thank my colleagues Prof. Yufan Zhao from Northwestern Polytechnical University, China, and Prof. Erina Joyee from University of North Carolina, Charlotte, for their help in organizing this special issue.

Among these, there are four review papers. The paper “Review on Field-assisted Additive Manufacturing of Stainless Steels” (e202503210, https://doi.org/10.1002/adem.202503210) by Prof. Tan and Zhang of Soochow University, China, discusses the application of magnetic, thermal, acoustic, and multifield strategies in AM of stainless steels, tuning grain structures, porosity, and residual stress to a better state. Magnetic and thermal fields can enhance melt-pool convection and acoustic fields lead to fragment dendrites. Deformation fields and external forces such as in-situ rolling or peening induce plastic strain for dynamic recrystallization. Prof. Wu from Jilin University reviewed ultrasonic-assisted AM across different materials (e202501744, https://doi.org/10.1002/adem.202501744). Ultrasonic assistance mainly helps in reducing porosity and microcracks, refining grain structures, and aligning ordered particles during the AM process. Process advantages, mechanisms, and challenges were thoroughly reviewed. Prof. Li and Wu from Xi’an Jiaotong University, China, reviewed 3D-printed multifunctional thermally deformed metamaterials (e202600011, https://doi.org/10.1002/adem.202600011). Thermal deformable metamaterials enable programable thermal expansion and deformation modes. Design principles, performance, and manufacturing processes for thermal deformable metamaterials were reviewed. The challenges in design-functionality optimization and manufacturing precision were also discussed. Prof. Liao from Iowa State University and Prof. Jin and Wang from University of Nevada Reno reviewed energy field-assisted AM of engineering thermoplastics (e202502252, https://doi.org/10.1002/adem.202502252). Energy fields in AM of thermoplastics are trying to minimize the fabrication defects, improving the building quality. Thermal, acoustic, magnetic, and electric field-assisted methods are used mainly in fused filament fabrication and selective laser sintering for fabrication of thermoplastics. Potential challenges and future research directions are discussed at the end.

The topics of research papers in this special section cover both 4D printing using smart materials and also field-assisted AM approaches.

Mo et al. in “On the Lightweight Potential of Laser Additive Manufactured NiTi Triply Periodic Minimal Sheet Lattices” (e202501910, https://doi.org/10.1002/adem.202501910) offer a compelling investigation into shape memory alloys. It demonstrates how laser energy input during micro-laser powder bed fusion dictates the 4D performance of NiTi triply periodic minimal surface (TPMS) lattices. It reveals a critical coupling between laser-induced thermal history and functional recovery: higher relative densities alter melt pool dynamics, promoting Ti₂Ni precipitation and lowering phase transformation temperatures and enhancing recoverable strain. This work proves that the lightweight potential and adaptive behavior of smart materials are directly governed by the energy dosage during manufacturing. Guo et al. developed a 4D-printed multifunctional PLA-based composite bone scaffold integrating near-infrared photothermal response, shape memory, antibacterial functionality, and cell response capabilities (e202501477, https://doi.org/10.1002/adem.202501477). ε-polylysine coating on the scaffold was found to enhance the antibacterial function, facilitating the proliferation and osteogenic differentiation of osteoblast cells. Peng et al. studied the electric field-induced alignment mechanism of carbon nanotubes and fibers within carbon fibers and carbon nanotube-reinforced polydimethylsiloxane composites using vat photopolymerization that produced TPMS sacrificial molds (2501490, https://doi.org/10.1002/adem.202501490). It shows that electric field arrangement significantly enhances the anisotropic elastic modulus of the TPMS samples. Zhang et al. studied that nanoscale precipitates in laser powder bed fusion of Cu–Al–Mn alloys are introduced via aging, focusing on their effects on phase transformation and superelasticity (e202502248, https://doi.org/10.1002/adem.202502248). Bandini et al. studied ultrahigh-speed electric field-assisted direct ink writing on flexible substrates. The field was found to facilitate filament deposition and reduce trace thickness during 3D printing (e202503101, https://doi.org/10.1002/adem.202503101). High substrate speeds of up to 30 m/s with enhanced resolution resulted in as thin as 150 nm dried polymer traces. The developed strategy achieved micron-scale resolution and controlled morphologies of conductive traces formed from conducting polymer writing of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate—poly(ethylene oxide) ink on flexible substrates. Li et al. fabricated TiNiCu strain glass alloys via laser-directed energy deposition (e202502937, https://doi.org/10.1002/adem.202502937). Nanoscale Ti(Ni, Cu)₂ precipitates were found in the austenite matrix, suppressing martensitic transformation and promoting the crossover strain glass transition behavior. The fabricated alloy exhibited quasilinear recoverable strain across a broad temperature range from −30 to 120 °C. The crossover strain glass transition facilitates the formation of martensite and adiabatic temperature changes.

Energy-assisted AM and 4D printing are and will still be hot topics around the world. Developing diverse energy field-assisted 3D printers is the current trend. Future work may focus on higher functional materials and building rates, using energy field-assisted methods in the space, oceans, and other harsh environments.