Progress towards Understanding the Synthesis and Behavior of Metals Far from Equilibrium: A SMD Symposium Honoring Enrique Lavernia on the Occasion of His 60th Birthday: Additive Manufacturing
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Composite Materials Committee
Program Organizers: Haiming Wen, Missouri University of Science and Technology; Suveen Mathaudhu, Colorado School of Mines; Yuntian Zhu, City University of Hong Kong; Manoj Gupta, National University of Singapore; Kaka Ma, Colorado State University; Troy Topping, California State University Sacramento; Yizhang Zhou, University of California, Irvine; Joshua Yee, Sandia National Laboratories; Dalong Zhang, Pacific Northwest National Laboratory; Yaojun Lin, Wuhan University of Technology; Fei Chen, Wuhan University of Technology
Wednesday 8:30 AM
February 26, 2020
Room: 31B
Location: San Diego Convention Ctr
Session Chair: Noam Eliaz, Tel-Aviv University; Lorenzo Valdevit, University of California – Irvine
8:30 AM Invited
High-throughput Alloy Design of Advanced Materials Using Additive Manufacturing: Dan Thoma1; 1University of Wisconsin, Madison
Alloy design of advanced materials requires a systematic evaluation of compositional and microstructural space during synthesis to optimize properties. To accelerate the alloy design process, high-throughput additive manufacturing (AM) methods have been developed. Firstly, directed energy deposition (DED) methods permit flexibility in compositional control by controlling the deposition rate of individual metal powders from up to 4 powder hoppers. Two example systems will be highlighted: 1) high entropy alloys (HEAs), and 2) bulk metallic glasses (BMGs). Refractory HEAs have been produced from elemental powders within 5 at.% of the desired composition, and up to 100 samples (a centimeter cube) can be fabricated per day. Similarly, 1 mm diameter “dots” of Mg-based BMGs can be fabricated with over 2000 samples per day. Secondly, selective laser melting (SLM) methods permit HT microstructural control to refine the mechanical response of the alloys. Examples on various alloys will be characterized.
9:00 AM Invited
Compositional and Structural Evolution of Passivation Layers in Heat- and Humidity-treated Aluminum Powder for Cold Spray Applications: Cameron Crook1; Maryam Azar1; Diran Apelian2; Daniel Mumm1; Lorenzo Valdevit1; Jasper Zebulon Lienhard3; Christopher Schuh3; 1University of California, Irvine; 2University of California, Irvine; Worcester Polytechnic Institute; 3Massachusetts Institute of Technology
Cold spray is an advantageous thermal spray technology due to the low intrinsic temperatures, minimal oxidation, preservation of feedstock microstructural characteristics, and the availability of a broad assortment of sprayable materials. Empirical knowledge suggests that the passivation layer of powder feedstocks strongly affects the critical impact velocity of the particle, and in turn the optimal processing conditions and the resulting mechanical properties of the coating. However, no comprehensive studies been performed to directly correlate the characteristics (composition, thickness and structure/crystallinity) of the native grown oxide layer to the critical impact velocity. High-purity Aluminum powders were manufactured by gas atomization and subjected to various temperatures and humidity levels using a fluidized bed system. Here we demonstrate these powders exposed to high relative humidities result in significant evolution of the passivation layer. We show that these microstructural/morphological evolutions directly correlate with a substantial increase in critical impact velocity and we identify three possible mechanisms responsible for the change through a combination of materials techniques, including XPS, FTIR, HR-TEM/STEM, and single particle impacts.
9:30 AM Invited
Micro-structure and Mechanical Behavior of Metallic Parts Made using Powder Bed Process Additive Manufacturing: Leila Ladani1; 1Arizona State University
Laser and electron beam technologies are the most common technologies used for production of metallic parts using additive technology. Although very versatile, variation in the process parameters can result in variety of grain sizes from equiaxed to columnar grains formed in a preferred orientation and a whole range of grain sizes which then results in unexpected mechanical behavior. This presentation summarizes our recent findings on the grain formation, size and orientation for multiple metals during this complex process. The effect of process parameters on the final micro-structure is discussed. Micro-scale mechanisms of plastic deformation and impact of columnar grain formation on these mechanisms are presented. New ideas on utilizing the ability to tailor the grain formation during the process in direction for designing new materials and micro-structures are presented.
10:00 AM Break
10:20 AM Invited
Formation of Non-Equilibrium Phases by Electrodeposition and a Novel Additive Manufacturing Process of Meniscus-confined Electrodeposition: Noam Eliaz1; 1Tel-Aviv University
Electrodeposition is a non-equilibrium process as it takes place under cathodic overpotential. Consequently, the phases formed are often not in thermodynamic equilibrium, and may be either undersaturated or supersaturated compared to their counterparts in the equilibrium phase diagram. In this presentation, examples such as formation of metastable fcc-Re and hcp-Ni in the Re–Ni and Re–Ir–Ni systems and non-equilibrium phases in the Zn–Ni system will be given. The effects of high internal tensile stresses developed in the coating due to co-deposition of hydrogen, hetero-epitaxial growth and hydride decomposition on the microstructure will be discussed. In light of Prof. Lavernia’s seminal contributions to additive manufacturing of metals, a novel atomic force microscope-based three-dimensional meniscus-confined electrodeposition developed in my lab will be presented.
10:50 AM Invited
Microstructure-property Development During Directed Energy Deposition of Austenitic Stainless Steels: Chris San Marchi1; Thale Smith2; Josh Sugar1; Julie Schoenung3; 1Sandia National Laboratories; 2Nanocore 3D; 3University of California, Irvine
The development of microstructure and properties during metal additive manufacturing is the result of the complex thermomechanical history imposed on the material. In the case of directed energy deposition (DED) of austenitic stainless steels, solidification and subsequent thermomechanical deformation strongly influence the microstructural evolution and resulting properties of the deposited material. While knowledge of analogous conventional processes like welding provide some insight to the microstructure-property relationships, the distinct length and time scales of DED must be considered to understand the unique multiscale microstructures that develop. Importantly, the large transient thermal gradients during deposition induce a complex elastic-plastic strain history, nonuniformity of mechanical properties (induced in part by plastic strains) and substantial residual stresses (intrinsically elastic). In this talk, DED of austenitic stainless steels is discussed with attention to microstructural evolution and strengthening mechanisms.
11:20 AM
Microstructure of Additively Manufactured and Laser Melted 316L Stainless Steel: Thomas Devine1; Yoon Hwa2; Joshua Yee3; Nancy Yang3; 1University of California; 2University of California, Berkeley; 3Sandia National Laboratories
The microstructure of laser melted 316L stainless steel is investigated as a function of laser power density, laser translation speed, and ambient gas flow. Samples were formed by additive manufacturing (LENS) of powders and by surface melting of a solid plate. In both types of samples, the optical microstructures are similar and are inhomogeneous on the scale of several microns. Two aspects of the inhomogeneous microstructures stand out. First, the mode of solidification changes from plane front to cellular with increasing distance from the fusion line. Second, banding occurs across the entire cross-section of the LENS hatch and across the cross-section of the surface melted tracks and of surface melted spots. Changes in solidification mode are associated with the spatial variation of the ratio of thermal gradient to solidification velocity. Banding is caused by high laser power and ambient gas flow. A mechanism of banding is proposed.
11:40 AM Cancelled
Research on Laser Additive Manufacturing Technology of TiC Particles Reinforced Inconel 718 Composites: Chen Bingqing1; 1Beijing Institute of Aeronautical Materials
In this work, the laser additive manufacturing technology of TiC particles reinforced Inconel 718 composites was explored, and the influences of laser processing parameters and TiC content on microstructure, microhardness and tensile properties of the composites were investigated. Using laser additive manufacturing technology, 5 wt.%, 10 wt.% and 50 wt.% TiC particles reinforced Inconel 718 composites have been successfully fabricated. It is indicated from the experimental results that when TiC particles were added into the metal matrix, the Vickers microhardness values and tensile properties of the composites were greatly increased. When the TiC content was 5 wt.% and medium laser energy input was adopted, the best combination condition between TiC and metal matrix was obtained. Complete and stable metallurgically combined interfaces could form, and the TiC particles distributed evenly and uniformly.