Additive Manufacturing: Materials Design and Alloy Development III -- Super Materials and Extreme Environments: Light Weight Materials
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Additive Manufacturing Committee
Program Organizers: Behrang Poorganji, Morf3d; Hunter Martin, HRL Laboratories LLC; James Saal, Citrine Informatics; Orlando Rios, University of Tennessee; Atieh Moridi, Cornell University; Jiadong Gong, Questek Innovations LLC

Monday 2:00 PM
March 15, 2021
Room: RM 3
Location: TMS2021 Virtual

Session Chair: Hunter Martin, HRL


2:00 PM  Invited
Architectured Interpenetrating Structures with Tailorable Energy Absorption in Tension: Zachary Cordero1; 1Massachusetts Institute of Technology
    Fiber-reinforced brittle-matrix composites can achieve exceptionally high energy absorption in tension relative to the monolithic matrix material. In woven and braided composites, high energy absorption results from two key mechanisms: (i) local hardening via reinforcement lock-up, which promotes damage delocalization, and (ii) conversion of the far-field tensile stress into a local compressive stress that extracts inelastic work from the brittle matrix phase. In this talk, I will show how these same mechanisms can be engineered into additively manufactured interpenetrating composites and interpenetrating lattices to achieve unprecedented combinations of energy absorption and strength. I will present two case studies that illustrate these principles: an additively manufactured, fully dense interpenetrating composite of 316L stainless and A356 and an interpenetrating lattice structure, termed chain lattice, that transforms brittle 3D-printable materials into damage-tolerant structures.

2:30 PM  
Al-Cu-Zn-Mg Alloy for Additive Manufacturing by Electron Beam Deposition: Marcia Domack1; Cecilia Mulvaney2; Christopher Domack3; Brandon Bodily4; Karen Taminger1; 1NASA Langley Research Center; 2University of Virginia; 3Analytical Mechanical Associates; 4Arconic Technology Center
    The application of fusion-based additive manufacturing (AM) to aircraft structural components is limited by the lack of high-strength aluminum alloys optimized for AM processing. High strength aluminum alloys (such as 7050-T7451) are difficult to process by AM because of their solidification cracking susceptibility and loss of volatile alloying elements such as Zn and Mg. The performance of a customized Al-Cu-Zn-Mg alloy wire feedstock was evaluated for AM utilizing electron beam deposition. Deposit microstructure, composition, occurrence of porosity and cracking, and post-heat treatment tensile and fracture toughness were correlated with deposition parameters. Post-heat treatment strength, ductility, and fracture toughness were lower than typical values for wrought 7050-T7451, related to significant losses of Zn and Mg and to porosity. Recommendations are offered for modifications to wire feedstock composition and adjustments to deposition conditions and heat treatment to enable AM of electron beam deposited material that has strength comparable to 7050-T7451 wrought products.

2:50 PM  
Development of High Strength and/or Corrosion-resistant Al Alloys with High Printability: Le Zhou1; Holden Hyer2; Abhishek Mehta2; Sharon Park2; Thinh Huynh2; Brandon McWilliams3; Kyu Cho3; Yongho Sohn2; 1Marquette University; 2University of Central Florida; 3CCDC Army Research Laboratory
    High strength and/or corrosion resistant aluminum alloys with improved printability (i.e., fully dense without flaws) are desired for additive manufacturing such as laser powder bed fusion (LPBF). Two strategies have been proposed and examined for various Al-alloys. The first approach is to in-situ refine the grain structure during LPBF solidification, as demonstrated by Zr and/or Sc modified AA5083, AA6061 and AlZnMg alloys. These modified alloys exhibited bimodal grain structure without cracking compared to large columnar grains with cracking in non-modified alloys. The Al3(Zr,Sc) served as heterogeneous nucleation sites during solidification and further contributed to precipitation strengthening with appropriate heat-treatment. The second approach is to utilize eutectic compositions with minimum freezing range, as demonstrated by AlSi10Mg and Al-10Ce alloys. These near-eutectic alloys typically showed no cracking regardless of LPBF parameters. Exceptional tensile and corrosion properties of these LPBF-specific alloys are documented and compared to wrought alloys of similar composition.

3:10 PM  
Ability of Creation of Aluminium Alloys with High Heat Conductivity Suitable for 3D Printing: Mann Viktor1; Krokhin Аleksandr1; Vakhromov Roman2; Ryabov Dmitriy2; Mikhaylov Ivan2; Kirill Nyaza2; Grol Mariya2; 1RUSSIAN Aluminum Management; 2Light Materials and Technologies Institute RUSAL Management
    Additive manufacturing is the most promising technology to widen the application of aluminium alloys for heat dissipation. It offers to expand the heat echanging efficiency by complicating the internal structure and branching the channels where the heat passes. However, to get a significantly higher efficiency of heat exchangers, complicating the structure is not enough. It is crucial to use an alloy with higher thermal conductivity and higher strength. Developing such powder aluminum alloy requires to take into account the fact that high strength and thermal characteristics have to be achieved after aging or annealing. The possible risk of violation the complex geometry due to high internal stresses means that the material should not demand quenching. This work presents the results of development of selective laser melting and heat treatment for the new Al-Si-Fe alloy, which has a thermal conductivity of 190 W/m·K and mechanical characteristics of medium-strength aluminum alloys.

3:30 PM  
High Strength WE43 Microlattices Manufactured by Laser Powder Bed Fusion: Holden Hyer1; Qingyang Liu1; Le Zhou1; Dazhong Wu1; Shutao Song1; Yuanli Bai1; Brandon McWilliams2; Kyu Cho2; Yongho Sohn1; 1University of Central Florida; 2CCDC Army Research Laboratory
    Mg-alloy WE43 has a high strength to weight ratio. In combination with complex lattice designs, with “intended” porosity, WE43 lattices have the potential for the ultimate lightweight structural material. Therefore, this study investigates the fabrication, compressive behavior, and fracture modes of 24 different WE43 lattice structures produced by laser powder bed fusion (LPBF). Utilizing cubic and tetrahedron designs, 900 mm3 lattices were designed in which unit cell type, strut diameter, and unit cell size were varied. The compressive behavior of the lattice structures exhibited oscillations in stress, showing many local maxima and minima, with a peak in stress near 5 % strain. The highest compressive strength, and associated specific strength, achieved was 48.6 MPa and 26.4 MPa·g-1·cm3, respectively. Two failure modes were observed, 45° shear fracture and crushing, suggesting little plastic deformation. Consequently, a direct relationship between the density and the compressive strength was observed, unaffected by unit cell type.