Bulk Metallic Glasses XVII: Alloy Development and Application I
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Yanfei Gao, University of Tennessee-Knoxville; Hahn Choo, University of Tennessee; Yunfeng Shi, Rensselaer Polytechnic Institute; Robert Maass, Federal Institute of Materials Research and Testing (BAM); Xie Xie, FCA US LLC; Gongyao Wang, Globus Medical
Wednesday 8:30 AM
February 26, 2020
Room: Cardiff
Location: Marriott Marquis Hotel
Session Chair: William Johnson, California Institute of Technology; Marios Demetriou, Glassimetal Technology
8:30 AM Invited
Rapid Discharge Forming of Metallic Glasses: A Novel Metals Manufacturing Platform: Marios Demetriou1; Kyung Hee Han1; Jong Hyun Na1; Maximilien Launey1; William Johnson1; 1Glassimetal Technology
Injection molding metals to net shapes like plastics has been an ambition of technologists for decades. Crystalline metals don’t soften gradually and continuously like plastics but abruptly collapse to a fluid liquid upon melting bypassing the viscous states that enable “thermoplastic” processing. “Metal Injection Molding” (MIM) is currently performed using powder mixtures of metal and plastic binder to mold “green” parts that are subsequently sintered to size following debinding. MIM is rapidly gaining prominence in metals manufacturing despite its elaborate and expensive multistep process. By virtue of being glasses, metallic glasses soften above the glass transition enabling “true” thermoplastic net shaping. Rapid Discharge Forming (RDF), where an electrical discharge uniformly heats metallic glass to the viscous “thermoplastic” states rapidly enough bypassing crystallization, is emerging as an effective means for injection molding metallic glasses. In this presentation, efforts to commercialize RDF injection molding and progress in part manufacturing will be discussed.
8:50 AM Invited
Structure-property-processing Relationships in Bulk Metallic Glasses Suggest a High, but Narrow Path to Success: Jan Schroers1; 1Yale University
Bulk metallic glasses combine plastic like processing with superb high-strength metal properties. Their processing opportunities originate from their high thermal stability, which has been explored for novel metal processing methods such as fused filament fabrication to 3D print, blowmolding to fabricate previously unachievable shapes for metals, and micro- nanofabrication. As BMGs are metastable, processing has to avoid crystallization, structural relaxation, and reduction of fictive temperature. We show here that minute structural changes, realized through processing conditions, can cause drastic effects on mechanical properties. Specifically, we reveal a flaw tolerance behavior of metallic glasses, a critical volume fraction of crystallinity for embrittlement, and a mechanical glass transition behavior. We will offer a mechanistic understanding based on local atomistic events controlling brittleness and ductility in metallic glasses. Utilizing suggested metallic glass paradigm requires careful considerations of all these phenomena to form high-strength metals like plastics with consistently high fracture toughness.
9:10 AM Invited
An Overview of BMG Additive Manufacturing Activities and Future Directions at NASA JPL: Douglas Hofmann1; Punnathat Bordeenithikasem1; 1NASA JPL/Caltech
This talk will survey some of the ongoing work in 3D printing of bulk metallic glasses and composites for potential spacecraft applications. BMGs have successfully been fabricated through a variety of processes, including powder bed fusion, directed energy deposition, laser foil printing, ultrasonic additive manufacturing and thermal spraying. Additionally, composites have been fabricated with interesting properties. A discussion of mechanical properties and potential applications will be presented.
9:30 AM Invited
Synthesis and Properties of BMG Type Nanoglasses by Thin Film Vapour Deposition: Hans Fecht1; 1Ulm University
Nanoglasses can be considered as non-crystalline solids which exhibit a glass-like atomic structure and contain a considerable number of internal interfaces. This metastable state of matter can be synthesized by thin film deposition from a BMG-type target among a variety of mother methods. Remarkably, all of these BMG based nanoglass specimen clearly exhibit an anomaly of the specific heat typical for the glassy state. Using a fully amorphous sputtering target of VIT105 and Au-based BMG the resulting nanostructures can be varied from monolithic amorphous to nanoglass and to columnar amorphous nanostructures at varying Argon base pressure. While in general glassy structures lack ductility, the nanoglass state exhibits superior mechanical properties achieving a remarkable level of plastic deformation in bending experiments. Further details, also in relation to a recent theoretical approach, will be discussed.
9:50 AM Cancelled
Research Progress in Ti-based Bulk Metallic Glasses: Ke-Fu Yao1; Jia-Lun Gu1; 1Tsinghua University
Ti-based bulk metallic glasses (BMGs) are very attractive due to their low density, high strength and high specific strength. However, for long time their glass-forming ability (GFA) is relatively low when compared with other bulk glassy alloy systems, such as Zr-based or Pd-based BMGs, despite that many progresses have been obtained in recent years. Then, improving the glass-forming ability, thermal stability and mechanical property of Ti-based glassy alloys is important and meaningful. Here, we'll report recent research progresses of Ti-based BMGs in Tsinghua university. The obtained results show many Ti-based alloys could also possess large glass-forming ability. Some of them exhibit a critical size of glassy samples larger than 20-30 mm. In addition, these Ti-based BMGs show high yield strength and high specific strength, together with good anti-corrosion property. The effects of alloying elements on the glass-forming ability and properties of Ti-based BMGs have been discussed.
10:10 AM Break
10:30 AM Cancelled
Formation of New Metallic Glass States by Melt-quenching Under High Pressure: Qiaoshi Zeng1; 1Hpstar
Metallic glasses have been demonstrated to have tunable energy states by various post-fabrication treatment, such as aging, thermal cycling, shot peening, etc. While the properties can be considerably altered, their structures are surprisingly indistinguishable by diffraction methods. In this talk, we will show our recent work on the exploration of distinct metallic glass states by quenching various melt under high pressures. New amorphous states were successfully obtained as indicated by the obvious XRD peak shifting (both in position and intensity) compared to as-cast samples at the same pressure-temperature conditions. The largely enhanced density of these new amorphous states indicates the formation of high-density amorphous (HDA) states. These findings provide important evidence for the existence of long-sought high-density liquid (HDL) which may generally exist in various metallic glass forming melt, and also may open up an era of synthesizing HDA metallic glasses with many novel properties that were not achieved before.
10:50 AM Invited
Comparison of Excess Entropy in Strong and Fragile Glasses: Hillary Smith1; Marios Demetriou2; Brent Fultz2; 1Swarthmore College; 2California Institute of Technology
The excess entropy of metallic glasses was recently found to be almost entirely configurational in origin. Experimental measurements of the vibrational entropy through the glass transition in Cu50Zr50 and Cu46Zr46Al8, in combination with calorimetry measurements of the total entropy, showed a similar result for both metallic glasses. A purely configurational transition was postulated by Gibbs and co-workers in early theories of the large heat of the glass transition. However, it remains unclear whether the result demonstrated for metallic glasses will hold true for all glasses. New measurements of the vibrational entropy of an extremely fragile Pt-based metal/metalloid glass and the canonical fragile glass, ortho-terphenyl, will be compared to previous results. Progress towards a ‘universal’ understanding of the entropy through the glass transition will be discussed.
11:10 AM Invited
Glass-forming Liquids Processed Under Ultrahigh Gravitational Accelerations: Mihai Stoica1; Jörg Löffler1; 1ETH Zurich
Bulk metallic glasses generally have compositions close to deep eutectics. Therefore, ultrahigh acceleration processing may be employed for direct and efficient identification of eutectic compositions in multicomponent alloys. The parent glass-forming alloys also tend to feature dispersed phases which are close to or beyond their thermodynamic and mechanical stability. This study describes a high-temperature ultrahigh acceleration processing technique which was designed and constructed in-house and applied on various alloys produced. Pure metals, used as standards, and binary and ternary alloy samples were melted in a special Al2O3-coated TZM (Ti–Zr–Mo) crucible and then slowly cooled during continuous acceleration of maximum 50,000g. Atomic-level stratification is shown to generate more phases than predicted by the Gibbs phase rule under normal gravity. Modified phase diagrams in which new compositional fields and their corresponding structures are inserted will also be presented and discussed.
11:30 AM Invited
Catalytic Metallic Glasses for Clean Energy Applications: Vahid Hasannaeimi1; Shristy Jha1; Maryam Sadeghilaridjani1; Sundeep Mukherjee1; 1University of North Texas
The chemistry and morphology of catalytic amorphous metals may be tuned to obtain hierarchical nanostructures for clean energy applications. Accelerated development of electro-catalysts requires efficient synthesis of morphologies that provides effective utilization of the active catalytic species and high dispersion. Unique combination of desirable properties and processing ability in metallic-glasses make them attractive for catalysis. Using scanning electrochemical microscopy (SECM) and scanning kelvin probe (SKP), we have mapped the electrochemical activity of a series of metallic glasses and show their efficacy in a number of catalytic reactions for fuel cells. Using this knowledge, we synthesized non-precious metallic glass compositions with high catalytic performance and good chemical stability as potential replacement of expensive noble metal catalysts.
11:50 AM Invited
Studying Phase Transitions in Slow Motion: Ultrafast-calorimetry Experiments on Bulk Metallic Glasses: Jörg Löffler1; 1ETH Zurich
Applying ultrafast differential-scanning calorimetry experiments on bulk metallic glass-forming systems that show sluggish crystallization kinetics, we are able to determine phase transitions more or less in “slow motion”. In this way we can discover new phase-transition pathways, such as a solid-solid phase transformation via metastable melting [1], and interrupt rapid cooling after a phase transition to study the thermophysical properties of this phase via melting it at rapid heating [2]. We thus can unravel hidden transient phases (incl. quasicrystals) and construct metastable phase diagrams. The technique also allows us to identify different types of monolithic metallic glass that show distinctly modified short-range order, and thus to generate a novel glass state that reveals stochastic nucleation at intermediate undercooling [3]. [1] S. Pogatscher, et al., Nature Comm. 7, 11113 (2016). [2] G. Kurtuldu, K.F. Shamlaye, J.F. Löffler, PNAS 115, 6128 (2018).[3] J.E.K. Schawe, J.F. Löffler, Nature Comm. 10, 1337 (2019).