PowderMet          AMPM          Special Interest

144 - Investigation of Free and Constrained Sintering of Ceramic Powder Systems at the Particle Length Scale
Aatreya Manjulagiri Venkatesh

In-situ 3D imaging has proved to be highly valuable for improving the understanding and modeling of sintering of metallic and glass powders. For ceramics, owing to the complex and fine architecture of the individual grains, a much better resolution is required. Hence the experimental studies conducted previously on ceramic sintering have mostly been with agglomerates, rather than at the length-scale of particles. This can now be dealt with by taking advantage of the outstanding features of the upgraded synchrotron at the ESRF. The resolutions and the scan times available at the ID16B beamline were used to perform in-situ phase contrast nano-holotomography analyses of both free and constrained sintering for several representative ceramic powder systems. A high temperature compact furnace was designed and fabricated for the same. A non-agglomerated alumina powder mixed with different volume fractions of inert inclusions, generating different constraints, was sintered at 1500°C. Complete 3D images were obtained with a voxel size as low as 25 nm with a fast and continuous acquisition, so as to depict particles and pores with enough details and follow the full sintering process. Subsequent quantitative image analyses were used to explore microstructural changes, including the densification and grain growth phenomena, both with and without the presence of inclusions throughout the sintering cycle.

086 - Fabrication of Lanthanum Zirconate Based Thermal Barrier Coatings Using Spark Plasma Sintering
Tejesh Dube, Indiana University - Purdue University Indianapolis

In this work, lanthanum zirconate (LZ) based thermal barrier coatings (TBCs) are fabricated using the spark plasma sintering (SPS) technique. Three different TBC systems are developed: pure LZ layer, bilayer LZ/718 nickel superalloy, and three-layer LZ/2D-inorganic compound/718 superalloy. Microstructure and phase analyses are conducted using scanning electron microscopy (SEM), x-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). Vickers hardness testing is used to evaluate the hardness and fracture toughness of the samples. Fabricating TBCs using SPS provides an alternative means to potentially reduce the fabrication time and costs. 

098 - Mechanical Properties of Cemented Tungsten Carbide with Nanocrystalline FeNiZr Binder 
Sean Fudger, U.S. Army Research Laboratory

The commercial use of cemented tungsten carbide (WC) spans across numerous applications.  Due to the extreme hardness and high modulus, provided by the ceramic (WC) phase combined with the added plasticity and resulting toughness contributed by the binder cobalt (Co) phase, cemented WC-Co is a good candidate for cutting tools, ammunition, and mining equipment.  In addition to being identified as a strategic and critical material from the Department of the Interior (DOI), Co has also been identified as "anticipated to be a human carcinogen" by the US Department of Health and Human Services (HHS).  Nanostructured FeNiZr is being evaluated as a plausible binder replacement to Co which doesn't exhibit these concerns.  Preliminary consolidations of WC-FeNiZr powders utilizing Field Assisted Sintering followed by Hot Isostatic Pressing have generated (near) fully dense samples with hardness values exceeding 16 GPa.  Electron Backscatter Diffraction and Transmission Electron Microscopy will be used to discuss to effects of the structure-property relationship herein.

155 - Microstructure and Mechanical Properties of FSLA Steel Produced by Metal Injection Molding
Lane Donoho, Advanced Metalworking Practices, LLC

An alloy, call FSLA (free-sintering low-allow), was designed and implemented for use with binder jet printing, however the powder is also suitable for metal injection molding. This work focuses on examining the mechanical properties and microstructure of the FSLA alloy and it's response to standard metal injection molding processes. The work also reviews the various heat treatments that can be utilized with the alloy to produce a range of properties for various applications. The microstructure and mechanical properties will be compared to the same alloy that has been produced by the AM process of binder jetting. The advantages and disadvantages of each process will be reviewed in response to cost of production and final properties.

235 - Metal Injection Molding of F75 (Co-28Cr-6Mo)
John Johnson, FAPMI, Novamet/Ultra Fine Specialty Products

Due to a combination of strength, wear resistance, corrosion resistance, and low magnetic permeability, Co-28Cr-6Mo is used in diverse applications ranging from smart phones to surgical implants. Historically cast to ASTM F75 specifications, many Co-28Cr-6Mo components are suitable for metal injection molding. Achieving F75 properties in the as-sintered state requires control of the interstitial content and microstructure, which are dependent on the starting powder chemistry and the sintering atmosphere as shown from sintering studies of metal injection molded F75 powders produced by gas- and water-atomization. The effects of hot isostatic pressing and heat treatment to further improve the mechanical properties are also investigated.

065 - Gate Size in Metal Injection Molds
Griffin Seidler, Ruger Precision Metals, LLC

In plastic injection molding, there are few more important dimensions for the quality of molded part than the gate size. A larger gate allows more material to fill the part during the packing phase of injection, compensating for volumetric shrinkage. Evidence shows that larger gate sizes in Metal Injection Molds benefit metal parts in a similar way. In certain Metal Injection Molding applications, it is sometimes desired to have little to no evidence of the gate on a finished part. Sometimes, this can lead part and mold designers into the trap of building the mold with undersized gates. On parts with relatively large wall thicknesses, this can cause issues including sinks, voids, flow lines, and sometimes cracks. These problems can be discovered before any steel is cut for a mold using a simulation software like AutoDesk Moldflow. This presentation will show how gate size affects different aspects of MIM part quality and how simulation can accurately predict potential issues related to gate size.

033 - Processing of Copper by Extrusion-Based Additive Manufacturing
Animesh Bose, FAPMI, Desktop Metal

Bound metal deposition (BMD) is a metal additive manufacturing (AM) technology that has its roots in metal injection molding (MIM). The process of BMD can be considered as a process that falls under the broad classification
of extrusion-based additive manufacturing (categorized by ASTM/ISO). This process has been used to carry out both rapid prototyping as well as low volume serial production of complex shaped parts some of which cannot be fabricated by traditional metal shaping processes. Pure copper is a material that possesses an excellent combination of both thermal and electrical conductivity and therefore has numerous industrial applications (heat sinks, heat exchanger, electrical contacts, motor components, etc.). Processing of pure copper by additive manufacturing is quite challenging. This paper will address some of the processing issues and properties that can be achieved with BMD of copper.

015 - Binder Jet Additive Manufacturing of Copper Using Single Pass Jetting
John Reidy, Desktop Metal

Copper is widely used for applications that require excellent thermal or electrical conductivity. The design freedom brought by additive manufacturing, paired with the properties of copper holds promise in a wide array of applications, from heat exchangers to components for electric motors. Binder jet additive manufacturing of copper has presented challenges with respect to achieving high density parts. This work details the use of a high throughput binder jet technology, Single Pass Jetting, to produce copper parts of variable complexity using a commercially available copper powder. Green parts were subsequently subjected to pressureless sintering and achieved high density. Sintered samples were characterized for conductivity and mechanical properties.

122 - Manufacturing of Pure Cu via Binder Jet Technology: Process and Properties
Lorenzo Marchetti, Digital Metal

Additive manufacturing can enable the production of metal prototypes and functionally optimized parts for several alloys. Pure Cu has excellent physical properties, making it the best candidate when high heat and electrical conductivities are needed, such as for heat exchangers, induction coils, and electronic components. Nevertheless, the performance of Cu components manufactured with more established methods can be limited from production process constrains, which may limit freedom of design or component dimensions.  A multi-step Additive Manufacturing process was used to manufacture pure Cu components. During printing, a binder is precisely deposited layer after layer on a powder bed, only where this is needed. After a curing step, the components green strength is reached, and the powder recirculated. The part is ready after de-binding and sintering.
Electrical and thermal performance, as well as chemical composition, microstructure, mechanical properties, and dimensional accuracy were assessed and compared to the MIM standard ASTM B883-19.

056 - Express Manufacturing of Large Metal Sintered Parts Combining FFF 3D Printing and Vibration Powder Casting
Maxim Seleznev, Markforged

Metal fused filament fabrication (FFF) 3D printing technology has low capital and operating costs, works with a range of metals and is health and fire safe. Although many parts can be finished in a day, large multi-centimeter cross-section solid parts could take several days to print, and, days or even weeks to wash out a wax component of the filament material binder. To avoid bulky cross-sections large metal FFF parts employ infill patterns. This strategy lightweights parts, however, for heavily loaded stamping or forging dies, such a solution cannot be used. Present work combines metal FFF printing of large, pressing/forging dies using infill with vibro-casting of dry powder into the infilled volume. Application of this technology greatly (>75%) cuts manufacturing time while attaining mechanical properties close (~80-85%) to solid printed/sintered parts. Effects of the infill geometry and powder size on mechanical properties and microstructure of the sintered parts are discussed.

083 - Fabrication of Li-Ion Battery Electrode Filaments Used for Fused Deposition Modeling 3D Printing Process
Eli Kindomba, Indiana University - Purdue University Indianapolis

Additive Manufacturing (AM) techniques have evolved to allow the fabrication of complex structures of various compositions in a wide range of applications. One promising use of AM is in the three-dimensional printing of battery cells through fused deposition modeling (FDM). Additive manufacturing technologies can enable the printing of complex and optimized 3D electrode architectures that maximize energy storage beyond what is possible in current 2D electrodes. However, challenges encountered in 3D printing battery electrodes involve the necessity to optimize filaments composition and electrochemical performances while maintaining printability and mechanical strength. In this study, we investigate the formulation, printability and material characterization of graphite/polylactic acid (PLA) filaments modified from a recipe in literature. While the graphite/PLA serves as the anode, we also investigate the formulation of cathode filaments. Those filament mixtures are studied and compared based on their printability, electrochemical performance, thermal and mechanical characteristics. Through this study, printed electrodes and separator materials can be assembled to form a fully 3D printed battery of complex desired shapes with optimized energy density and sufficient mechanical strength.

126 - Generative Design and Topology Optimization Based 3D Printing via Metal Fused Filament Fabrication (MF3) 
Saleh Khanjar, University of Lousiville

Metal fused filament fabrication (MF3) 3D printing technology is a combination of fused filament fabrication and sintering process. Generative design and topology optimization tools typically identify optimal distribution of material for a part while simulating the part’s behavior when subjected to expected loads. Such tools have been utilized to minimize material consumption and weight, without compromising on the performance of the parts printed using different AM technologies. However, in contrast to other AM technologies, MF3 technique involves debinding and sintering the 3D printed green part to achieve high density final product. This work implements generative design and topology optimization using Altair and Autodesk Fusion360 softwares to investigate its limitations in MF3 3D printing. Additionally, the effect of design optimization on structural integrity of parts 3D printed via MF3, from green to sintered state was studied. The application of design optimization to MF3 revealed promising results, addressing component efficiency and sustainability.

148 - Mechanical Properties and Microstructures of Additively Manufactured Platinum Alloys
Teresa Frye, Techform

Additively manufactured platinum alloys are relatively new to the market and benefit greatly from increased data on mechanical properties and microstructures. Multiple powders and machine outputs are tested to determine metallurgical properties and data is reported in both the as-printed and hot isostatic pressed conditions. Comparisons with investment cast samples produced in the same alloys are provided to highlight differences in each method of manufacture. 

109 - Magnesium Advances in Additive Manufacturing and Powder Metallurgy
Rajiv Tandon, Luxfer Magtech

Interest in the use of magnesium alloys in aerospace, automotive, consumer electronics, and in orthopedic products are driven by the need for light weighting and/or to achieve higher fuel efficiency, along with magnesium’s biocompatibility.   Significant progress has been made in the last decade on investigating magnesium alloys including WE43 (Mg-4Y-3Nd-0.5Zr), AZ91 (Mg-9Al-1Zn), and binary alloys including Mg-Ca using additive manufacturing. Laser powder bed fusion (LPBF) has been the preferred technology of choice. High as-deposited density greater than 99.5% have been reported. Reported yield strengths of additively manufactured AZ91D range from 250-280MPa with ultimate strength ranging from 320 to 350MPa. For additively manufactured WE43 reported yield strength range from 150-200 MPa with ultimate strength from 250 to 300 MPa. These properties are higher than typical cast AZ91 and WE43.   Powder metallurgy (PM) also offers the possibility to tailor compositions and develop unique microstructures. Traditional PM sintering processes using magnesium are challenging due to its affinity for oxygen and the presence of a surface passive film. The use of high purity atmosphere and liquid phase have shown promise of overcoming these challenges. More successful commercial PM approaches involve the use of alloyed powder, followed by hot pressing and extrusion.  This paper will summarize recent trends and the potential and challenges of using magnesium alloy powders in powder metallurgy and additive manufacturing processes. 

146 - High Strength Aluminum Alloys by Additive Manufacturing
Juha Kotila, EOS Finland

High strength aluminum alloys have become very attractive on metal AM. The traditional, wrought high strength aluminum 2000-, 6000- and 7000-series alloys have unique combination of light weight and high strength. But Additive Manufacturing of identical aluminum alloys in high quality without mixed, costly additives has proven to be challenging. Until now.   This paper presents properties of 2139-series aluminum intended for AM applications requiring high mechanical properties in room temperature and especially elevated operation temperatures typically experienced in electric and combustion engine applications found in aviation, transportation, racing and space industries. Comparison of properties to wrought high strength aluminum alloys as well as other type AM aluminum grades will be made against the Al 2139 AM parts build using an metal AM printer and Al 2139 AM process. Paper will focus on performance of Al 2139 AM parts in long term operating conditions experienced in engine applications.

504 - Coated Iron Powder in Soft Magnetic Applications, Challenges, and Benefits
Kalathur Narasimhan, FAPMI, P2P Technologies

Coated iron powder for soft magnetic applications was developed in 1989-90 by Hoeganaes corporation. The availability of pure atomized iron powder and higher density processes made the coated iron powder technology attractive for replacing lamination steels in some applications. Minimization of eddy currents in AC applications was achieved very effectively. However larger coercive force in compacted coated powder compared to lamination steels produces higher hysteresis losses. Additionally coating results in air gap between iron powder particles which leads to lower permeability. This presentation discusses benefits of coated powder technology .3D printing of soft magnetic materials is also discussed.

510 - Cold Sintering Assisted Warm Compaction for Densification and Strengthening of Soft Magnetic Composites
Ramakrishnan Rajagopalan, Penn State University

Cold sintering is a low temperature transient liquid phase sintering process that has been used to densify ceramic materials at modest temperatures as low as 300°C. We demonstrate that the process can be extended to powdered metals and can improve significantly the green strength of powdered iron compacts formed under warm compaction conditions. Surface modification of iron powders was done to deposit an ultrathin hydrated iron phosphate layer on the surface. The powders when compacted at 100°C yield a dense compact with green strength as high as 75 MPa which is almost 2.5 times more than the warm compacted controls. Detailed microstructural study using Transmission Electron Microscopy revealed the nature of the interphase that imparted the large cohesive strength under the cold sintered assisted warm compaction. The increased green strength made the process conducive to produce iron compacts suitable for green machining. Furthermore, the samples when subjected to conventional high temperature sintering conditions yielded a fully sintered iron compact with density > 7.2 g/cc. 

505 - Cold Spray Additive Manufacturing of Soft Magnetic Materials for Electric Motor Applications
Fabrice Bernier, National Research Council Canada

Additive manufacturing is a promising alternative for the fabrication of soft magnetic materials as it offers higher shape flexibility compared to traditional manufacturing methods.  It could enable new design solutions to meet increasing electric motor requirements such as lower cost, higher efficiency, increased power density and decreased torque ripple. In this paper, cold spray additive manufacturing was used for high volume (several kg/hr) processing of iron-based soft magnetic materials with high mechanical properties. Several solutions to build components with low iron losses were investigated: optimization of spray parameters, use of different ferrous alloy compositions and use of individual insulation layer. In parallel, the effect of process parameters (temperature and pressure, surface condition and preparation, laser assistance) on the microstructure and their impact on mechanical properties will be presented. The obtained results will be compared to those found in the literature for traditional fabrication methods and other additive manufacturing technologies. Finally, the advantages of processing hard and soft materials using a single additive manufacturing techniques will be discussed in the context of electric motor applications.