Heterostructured and Gradient Materials (HGM V): New Mechanistic Discoveries Enabling Superior Properties: Heterostructured Materials I: Fundamentals
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 8:30 AM
March 20, 2023
Room: Aqua 314
Location: Hilton
Session Chair: Amit Misra, University of Michigan; Xinghang Zhang, Purdue University
8:30 AM Invited
Deformation Mechanisms in Laser Processed Nano-eutectics: Amit Misra1; Jian Wang2; 1University of Michigan; 2University of Nebraska-Lincoln
Al-Al2Cu and Al-Si cast eutectic alloys were refined to nanoscale by laser surface remelting producing nano-lamellar and nano-fibrous morphologies, respectively. Both heterostructures comprising of relatively soft (Al) and hard (Al2Cu or Si) phases exhibited ultra-high strength and strain hardening. Deformation mechanisms are characterized using in situ straining in electron microscopy and atomistic modeling. In both alloys, plastic flow homogeneity increased with increasing heterogeneity of the nanoscale microstructures, but due to different mechanisms. The nano-lamellar morphology exhibited unusual shear modes in the hard Al2Cu phase due to interface crystallography and defect energetics favored slip transmission. In Al-Si, there is no direct slip transmission across interfaces but the propagation of nano-cracks is suppressed by surrounding Al that exhibits high strain hardening, retaining good tensile ductility of the sample. The role of the interfacial mechanisms, and microstructural length scales and morphology in enhancing plastic homogeneity in heterogeneous microstructures is discussed.
9:00 AM
Mechanical Anisotropy Effects on Strength and Deformability in Nanolaminates Containing 3D Interfaces: Justin Cheng1; Shuozhi Xu2; Jon Baldwin3; Mauricio De Leo1; Irene Beyerlein4; Nathan Mara1; 1University of Minnesota Twin Cities; 2University of Oklahoma; 3Los Alamos National Laboratory; 4University of California Santa Barbara
Bimetallic nanolamellar composites have been studied extensively to probe the influence of interface structure on mechanical properties in nanocrystalline alloys. Previously, we have shown that Cu/Nb nanolaminates incorporating 3D interfaces (3D Cu/Nb) containing chemical, crystallographic, and structural nanoscale heterogeneities in all spatial dimensions have remarkable strength and deformability compared to 2D interface counterparts (2D Cu/Nb) under in situ micropillar compression normal to interface planes. In this work, we combine 3D compression results at normal and 45° inclination to interfaces to show that 3D Cu/Nb behaves more isotropically than 2D Cu/Nb and that 3D interfacial shear strength exceeds that of 2D interfaces. We couple these results with in situ TEM nanopillar compression and post mortem TEM of micropillar compression and discuss the microstructural origin of high strength and deformability in 3D Cu/Nb in terms of dislocation-interface interactions at the atomic and nano scales.
9:20 AM Invited
Designing Materials with Heterogeneous Microstructure via Additive Manufacturing: Matteo Seita1; Karl Sofinowski2; Shubo Gao2; Crystal Feng Ji2; 1University of Cambridge; 2Nanyang Technological University
One of the defining features of fusion-based additive manufacturing (AM) processes is the localized melting of metal by a high-energy source, which fuses the material together point by point into a 3-D part. By varying the processing parameters at any point across the build, it is possible to control the solidification of the material and drive the formation of different microstructures. This unique capability opens the path to designing and producing metal parts with arbitrary microstructures from the bottom-up. Here, we give two examples of this strategy and produce stainless steels with heterogeneous microstructures and unique mechanical properties. The first consists of samples with crystallographic texture gradients, which exhibit superplastic-like behavior. The second involves lamellar samples comprising of hard and soft microstructures, which evince additional—and tunable—hardening mechanisms. These two examples showcase the possibility of designing parts with advanced functionalities by controlling the microstructure of materials site-specifically during AM.
9:50 AM
Progress in Heterostructured Materials: Yuntian Zhu1; 1City University of Hong Kong
Strong and tough materials are desired for light-weight applications such as electric cars and aerospace applications. Recently, heterostructures are found to produce unprecedented strength and ductility that are considered impossible from our textbook knowledge and materials history. Heterostructured materials consist of heterogeneous zones with dramatic (>100%) variations in mechanical and/or physical properties. The interaction in these hetero-zones produces a synergistic effect where the integrated property exceeds the prediction by the rule-of-mixtures. Importantly, HS materials can be produced by current industrial facilities at large scale and low cost. There are many scientific issues with such materials that challenge the communities of experimental materials science and computational material mechanics. Heterostructured materials is quickly becoming a hot research field. In this talk I’ll present the progress in heterostructured materials as well as future challenges and issues.
10:10 AM Break
10:30 AM Invited
Mechanics of Extremely Heterogeneous Materials: Ting Zhu1; 1Georgia Institute of Technology
Recent development of heterogeneous materials such as eutectic high-entropy alloys processed by additive manufacturing and gradient nanotwinned metals produced by electro-deposition raises fundamental questions on the role of extremely fine microstructural heterogeneities in controlling mechanical behavior of these novel material systems. We combine mechanics modeling and experimental characterization to unravel the extra strengthening effects of microstructural gradients and resultant plastic strain gradients and back stresses relative to their homogeneous counterparts. Quantitative comparison is made between modeling and experimental results, highlighting the less appreciated notions of different types of back-stress hardening or different stages of extra hardening that operate in materials with extremely complex microstructural heterogeneities. Mechanistic insights are gained toward further enhancement of the strength-ductility synergy in extremely heterogeneous materials.
11:00 AM Invited
Constitutive Model and Finite Element Analysis of Heterostructured Materials: Hyoung Seop Kim1; Yongju Kim1; 1Pohang University of Science and Technology
The bimodal structure, one of the various heterogeneous microstructures, has been studied in an attempt to induce desirable strength-ductility synergies. We developed a physical-based constitutive model which represents the deformation mechanism well considering the evolution of geometrically necessary dislocations and statistically stored dislocation densities. Even though there are many complex correlations of grain size, volume fraction, and spatial distribution of soft coarse grain/hard fine grain in a bimodal structure, the bimodal structure-property linkage can be explored by adopting microstructure-based FEM simulations. This work demonstrates that the bimodal microstructure-property linkage can be analyzed quantitatively to facilitate finding optimal heterogeneous equiaxed bimodal structures.
11:30 AM Invited
Work Hardening and Radiation Response of Gradient Alloys: Tianyi Sun1; Zhongxia Shang1; Xinghang Zhang1; 1Purdue University
Metallic materials with gradient microstructures usually exhibit unique mechanical properties. FeCrAl and T91 alloys are promising cladding materials for next generation nuclear reactors. In this presentation, we will present the influence of gradient microstructures of FeCrAl and T91 alloys on their mechanical behavior. In situ micropillar compression studies showed the gradient alloys have good work hardening ability depending on their average laminate grain sizes. The radiation response of gradient alloys was investigated by using in situ radiations. The radiation damage, such as defect and He bubble distributions, depends on misorientation angle suggesting a strong capacity of non-equilibrium grain boundaries in accommodating radiation damage. The insight for the design of gradient materials with unique mechanical behavior and radiation tolerance will be discussed.