Heterostructured and Gradient Materials (HGM V): New Mechanistic Discoveries Enabling Superior Properties: Heterostructured Materials II: Structure Design
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Shaping and Forming Committee, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Yuntian Zhu, City University of Hong Kong; Kei Ameyama, Ritsumeikan University; Irene Beyerlein, University of California, Santa Barbara; Yuri Estrin, Monash University; Huajian Gao, Nanyang Technological University; Ke Lu, Institute of Metal Research; Suveen Mathaudhu, Colorado School of Mines; Xiaolei Wu, State Institute of Mechanics, Chinese Academy of Sciences

Monday 2:00 PM
March 20, 2023
Room: Aqua 314
Location: Hilton

Session Chair: Kei Ameyama, Ritsumeikan University; Andrea Hodge, University of Southern California


2:00 PM  Invited
Design of Heterostructured High Entropy Alloys for Superior Mechanical Properties at Cryogenic-to-ambient Temperatures: Cheng Zhang1; Enrique Lavernia1; 1University of California Irvine
    The highly tunable properties of high-entropy alloys (HEAs) provide extraordinary potential for critical structural applications, especially under extreme conditions. However, it is still a challenge for HEAs to achieve ultrahigh engineering tensile strength over 2 GPa with reasonable ductility. Here, with the introduction of heterogeneous microstructure, we report on a FeNiCoAl-based HEA that can show a superb combination of mechanical properties at cryogenic-to-ambient temperatures. Experimental results, obtained from TEM, TEM-based PED, and EBSD, demonstrate that the heterogeneous microstructure triggers high hetero-deformation induced hardening and facilitates the accumulation of dislocations. The macroscopic “loading-unloading-reloading” cyclic tensile tests confirm that hetero-deformation induced hardening plays a significant role in strengthening the alloy during deformation. Details about the difference in the sequence of phase transformation in fine grains and coarse grains caused by heterogeneity will be shown. The strategy for designing heterostructured HEAs with ultrahigh strength-ductility synergy will also be presented.

2:30 PM  Invited
Deformation Domains in Heterogeneous Nanostructured Inconel: Andrea Hodge1; 1University of Southern California
    Nanotwinned (NT) alloys were synthesized via magnetron sputtering and subjected to an aging treatment which led to the evolution of a heterogeneous nanostructured material with a unique and complex gradient grain topology. The heterogeneous microstructure contains regions consisting of columnar NTs, nano-grains, and abnormally large grains with diameters greater than 1 µm, which represents a material with a wide range of grain sizes and morphologies. The microstructure of the abnormal recrystallization region included rafted structures, M23C6 and δ precipitates which will be discussed in detail. Furthermore, the mechanical behavior will be correlated to the microstructural evolution of the alloy in order to highlight the various deformation domains.

3:00 PM  
Application of Harmonic Structure Design to a CrMnFeCoNi High Entropy Alloy: Kei Ameyama1; Hiroshi Fujiwara1; 1Ritsumeikan University
    The harmonic structure is a recently introduced concept paving the way for engineering metallic materials to achieve excellent mechanical performance. They consist of soft coarse-grained regions (Core) that are three-dimensionally surrounded by a connected network of hard ultra-fine grained regions (Shell). The interaction in these Core-Shell regions produces a synergistic effect, during plastic deformation, leading to superior mechanical properties that are extremely important in practical applications. In the present study, microstructure evolution and mechanical properties of the harmonic structure designed CrMnFeCoNi high entropy alloy was examined. As the results, due to its peculiar microstructural characteristics, the harmonic structure designed CrMnFeCoNi HEA demonstrated a combination of high strength, large uniform elongation, and large total elongation to failure, simultaneously, partially via the twinning deformation.

3:20 PM Break

3:40 PM  
Multiscale and Hierarchical Laminated Steel Structures with Superior Strength-ductility Synergy via Additive Manufacturing: Xipeng Tan1; Shubham Chandra2; 1National University of Singapore; 2Nanyang Technological University
    Laminated metal structure is a conventional form of heterostructured materials, which consists of alternating layers of soft and hard metallic phases. Here, we design and build novel laminated metal structures with H13 tool steel and 316L stainless steel powders using directed energy deposition additive manufacturing method. The additively manufactured laminated steel structures exhibit multiscale and hierarchical lamellar microstructures that are tunable, leading to superior synergy of strength and ductility. Microstructural heterogeneity and its resultant hetero-deformation induced strengthening and toughening mechanisms in the additively manufactured heterostructured samples are examined. This work provides new insights to design and directly manufacture high-performance bulk heterostructured materials via additive manufacturing.