Additive Manufacturing of Metals: Microstructure, Properties and Alloy Development: Other Miscellaneous Materials/Alloys
Program Organizers: Prashanth Konda Gokuldoss, Tallinn University of Technology; Juergen Eckert, Erich Schmid Institute of Materials Science; Zhi Wang, South China University of Technology
Wednesday 8:00 AM
October 20, 2021
Room: A115
Location: Greater Columbus Convention Center
Session Chair: Roman Maev, University of Windsor
8:00 AM
3D Printing of the Half-Heusler Alloy Nb1-xCoSb, A Case for Ternary Thermoelectric Materials: Muath Al Malki1; David Dunand1; G. Jeffrey Snyder1; 1Northwestern University
The continuous development of thermoelectric materials in the past decades led to the improvement of the dimensionless figure of merit and ultimately the overall device efficiency. However, synthesis and manufacturing of electronic materials in general, and thermoelectric materials particularly, requires delicate attention to attain the planned electronic and thermal properties. Furthermore, most of the conventional synthesis techniques, such as the hot pressing, limit the shape of the synthesized material; restricting them from being used in wide range of applications, such as wearable devices. The literature of 3D printing of thermoelectric materials, so far, is limited to binary materials ( Bi2Te3,PbTe,..). We are here showing the case for 3D printing of the half-Heusler alloy Nb1-xCoSb, in which we tackle the problems of secondary phases formation, porosity control and the relation of all that to the transport properties. This should bridge the gap towards printing of other ternary and quaternary thermoelectric systems
8:20 AM
Defect Free Pure Molybdenum Processed through Electron Beam Melting: Patxi Fernandez-Zelai1; Chris Ledford1; Elizabeth Ellis2; Quinn Campbell1; Andres Marquez Rossy1; Michael Kirka1; Donovan Leonard1; 1Oak Ridge National Laboratory; 2Y-12 National Security Complex
Electron beam melting (EBM) additive manufacturing (AM) is an attractive technology for printing refractory materials as preheating can mitigate against many cracking mechanisms. The majority of existing molybdenum research is focused on laser based processing with relatively little EBM work. In this presentation we share recent work on EBM processing of molybdenum. We observed anomalous microstructures consisting of sharp {001}, {111}, and mixed {001} & {111} crystallographic fibers in the build direction. The preference for these build direction fibers is dependent on the imposed surface energy density and which is likely due to changes in the weld pool morphology. Detailed microscopy demonstrates that columnar grains consist of much finer equiaxed subgrains suggesting large process induced stresses which drive plastic deformation. This work demonstrates that molybdenum may be processed crack-free through EBM AM. Furthermore, the resulting build direction fiber may be controlled, and exploited, towards fabricating components with optimized engineering properties.
8:40 AM
Fabrication of Pure Tungsten Using Electron Beam Powder Bed Fusion: Christopher Ledford1; Michael Kirka1; Patxi Fernandez-Zelaia1; Julio Ortega Rojas1; Andres Marquez Rossy1; Yutai Kato1; 1Oak Ridge National Laboratory
Refractory materials used in high temperature applications can benefit greatly from the novel processing techniques of additive manufacturing. These techniques can be applied to particularly difficult to process materials such as pure Tungsten to produce complex geometries. Obtaining high density and defect free material is not a trivial task due to their high melting points and often requires high processing temperatures. Here we present our work on the processing of pure Tungsten using electron beam powder bed fusion to produce fully dense, crack-free material along with evaluations of the microstructure and mechanical properties for varying processing conditions.
9:00 AM
Design of Wire-arc Additive Manufacturing of Functionally Graded Alloy from P91 Steel to Inconel 740H Superalloy Using High-throughput Method: Xin Wang1; Soumya Sridar1; Michael Klecka2; Wei Xiong1; 1University of Pittsburgh; 2Raytheon Technologies Research Center
The composition-process-structure-property relationship in dissimilar alloys is critical for successful manufacturing. In this work, an attempt was made to understand such a relationship for wire-arc additive manufacturing (WAAM) of dissimilar alloy from P91 steel to Inconel 740H superalloy. More than 400 sets of data, including composition, microstructure, hardness, ductility, and porosity, were obtained along the composition gradient introduced by WAAM. The CALPHAD (Calculations of Phase Diagrams) method was used to predict the additional features, such as freezing range, phase fractions, and heat capacity, to enrich the experimental datasets. Finally, a statistical approach was applied to estimate the variation in hardness, porosity, and ductility as a function of the composition gradient. The proposed method shows an advantage in generating large datasets of a large alloy composition space and provides an effective way for revealing the composition-process-structure-property relationship.
9:20 AM
Effect of Heat Treatment on Stainless Steel 420 And Inconel 718 Multi-material Structures Fabricated Laser Directed Energy Deposition: Beytullah Aydogan1; Himanshu Sahasrabudhe1; 1Michigan State University
Additive manufacturing techniques such as laser directed energy deposition (laser DED) can fabricate multi-material structures (MMS) in a near single step. Many components fabricated via laser DED require post-processing operations such as heat treatment and this is challenging for MMS. In this study, laser DED fabrication and heat treatment of stainless steel 420 (SS420) and Inconel 718 (IN718) MMS is investigated. Different compositions of SS420 and IN718 alloys for the multi-material regions were investigated and performance were found to be weaker than the parent materials. The present study improved this multi-material regions’ performance by devising a specialized heat treatment for the SS420 and IN718 multi-material structures. The mechanical performance was correlated to the microstructural features, before and after heat treatment, using destructive and non-destructive techniques. The result was a novel SS420+IN718 mixture chemistry that had properties comparable to the parent alloys, thus eliminating a weak link in the MMS.
9:40 AM
Process-property Relationships of Additively Manufactured Multi-material NiZnCu-ferrite Soft Magnetic Composites: Caleb Andrews1; Li Ma2; Ryan Carter2; Ian McCue2; Joseph Sopcisak2; Mitra Taheri1; 1Johns Hopkins University; 2The Johns Hopkins University Applied Physics Laboratory
Recent advances in multi-material additive manufacturing (AM) have enabled the production of more complex magnetic materials, including soft magnetic composites (SMCs). Our prior research has demonstrated the ability to manufacture metal-on-metal NiZnCu-ferrite SMCs with high permeability and acceptable core loss, but poor properties for high frequency applications and high porosity. Utilizing process simulations and high-resolution electron backscattering diffraction (HR-EBSD) analysis, variables were identified that could serve to improve the magnetic properties and reduce defects within this multi-powder system. We demonstrate an optimization study, informed by multiple modeling techniques and device production/analysis, that indicates a pathway to producing more dense, higher performance, and rare earth element free SMCs. It is critical that AM can meet the growing need for lighter and more geometrically complex electric motors and devices that conventional processes cannot, and this research aims to provide a model and method to achieve this.