Bulk Metallic Glasses XVII: Alloy Development and Application II
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
Thursday 8:30 AM
February 27, 2020
Room: Cardiff
Location: Marriott Marquis Hotel
Session Chair: Jianzhong Jiang, Zhejiang University; Jan Schroers, Yale University
8:30 AM Invited
Thin Film Metallic Glass Broad-spectrum Mirror Coatings: Tatiana Ștefanov1; Harsha Maraka1; Wim Sillekens2; David Browne1; 1University College Dublin; 2European Space Agency
The potential of metallic glasses for applications as optical mirrors for space was investigated. Various alloy compositions were developed using the rule of mixtures, in which the property of interest was the reflectivity of the pure components across a range of wavelengths from UV to near-IR. Composition choice was limited by the available method of synthesis by electric arc melting. After a preliminary study where the reflectivity of different bulk alloys was measured in the visible range, Al82.32Ni4.64Y0.04Zr13 and Zr56.6Cu29.6Al6.4Ag7.4 alloys were selected as targets for physical vapor deposition (PVD). Thin film metallic glasses were produced by PVD via magnetron sputtering on silicon carbide substrates. The structure, roughness, and hardness of the films were investigated. The predicted reflection was compared with the measured values for wavelengths between 250 nm and 2000 nm. The Al-based alloys were better optical reflectors, but the Zr-based ones were harder and offer higher thermal stability.
8:50 AM Cancelled
Atomic Dynamics Evidence for Configuration Memory in Metallic Glasses: Xiaodong Wang1; Tianding Xu1; Qing Yu1; Qingping Cao1; Jianzhong Jiang1; 1Zhejiang University
Although the memory effect has been reported in disordered materials, the underlying mechanism on the atomic scale is still unclear. By in situ probing atomic dynamics in an Au-based metallic glass (MG), we provide the first evidence that the glass exhibits a pronounced annealing-induced configuration memory effect at around pre-annealing temperature during heating, which could be erased by increasing temperature into the supercooled liquid region. A physical scenario for this phenomenon can be understood in the framework of potential energy landscape, i.e. annealing makes the energy of MG sample locate in a deep basin, in which the movement of atoms could be changeable in subbasins on the subsequent cooling and heating. Our findings open up a new perspective to visualize the structure of glass and will trigger useful hints to widen their applications as functional materials.
9:10 AM Cancelled
Effect of Tool Speeds on Joint Characteristics in Friction Stir Spot Joining Zr-based BMG to Al Alloy: Jason Silberman1; Harry Chang1; Danny Ventura1; Kylie Dodge1; David Yan1; 1San Jose State University
Bulk metallic glasses (BMGs) are very attractive to a range of military, medical and industrial applications due to its high strength, elasticity, corrosion resistance and soft magnetic properties. However, size limitation is still a long-standing problem for engineering applications as structural materials. The employment of joining technique in BMGs can be an effective approach to overcome this size restriction, though it remains a major challenge across multiple length-scales. Friction stir welding is a novel solid-state joining process which makes it a strong candidate for joining BMGs or BMG to other crystalline materials. But studies on the friction stir spot joining Zr-based BMG to Al sheet are limited. In this present study, a range of friction stir spot joining Zr-based BMG to Al sheet trials were carried out. The effect of tool speeds on the joint characteristics was studied in relation to the joint strength and processing force, torque and temperature.
9:30 AM Invited
Measuring Metallic Glass Viscosities Over Wide Composition Ranges: Sebastian Kube1; Will Polsky1; Rodrigo Miguel Ojeda Mota1; Kevin Ryan1; Jan Schroers1; 1Yale University
Amongst the most fundamental quantities for the description of a metallic glass (MG) are the viscosity η(T) and the fragility parameter, which are commonly related to the glass forming ability. Measuring these is challenging and data have only been reported for few compositions and systems. By contrast, no comprehensive experimental data exist thus far to reveal how the viscosity and fragility change within a system across a wider composition range. Fundamental questions therefore remain unanswered, for example whether the fragility and the glass forming ability are directly correlated for MGs. Here, we present first experimental strategies and results to measure the viscosity and fragility across wide composition ranges and across various MG systems. Since cost and required time per MG composition are comparatively small, we aim to implement these strategies in a high-throughput fashion.
9:50 AM Break
10:10 AM Invited
Solvent-rich Magnesium-based Bulk Metallic Glasses in the Mg–Pd–Ca and Mg–Pd–Yb Alloy Systems: Sidra Jilani1; David Miskovic1; Kevin Laws1; 1University of New South Wales
Magnesium-based metallic glasses are well-known for their low density, high specific strength and potential as resorbable biological implant materials. In this study a range of magnesium-rich (85-87 atomic percent) metallic glasses are developed from the Mg–Pd–Ca and Mg–Pd–Yb alloy systems. A solvent-rich amorphous alloy design method and properties of these amorphous alloys shall be presented. It is found that alloys within the composition range Mg86.4-87Pd7-7.7Ca5.8-6 and Mg86.4-87Pd7-7.7Yb5.8-6 are completely amorphous when copper mould-cast in sections ≥1mm diameter. These alloys exhibit hardness of 2.7-3.2 GPa, Young’s modulus of 62-64 GPa and density of 2.15-2.35 g/cm3 for Ca- and 2.81-2.96 g/cm3 for Yb-containing glasses.
10:30 AM
Metallic Glasses for Space Mechanism Applications: Andrew Murphy1; Rik Stewart2; Zahari Zlatev2; Martin Humphries3; Andrew Norman4; David Browne1; 1University College Dublin; 2Reliance Precision Limited; 3SpaceMech; 4European Space Agency
There is a growing interest in developing space mechanisms that overcome the engineering challenges associated with long-term space flight/operation, e.g. the need for lubrication, mechanism activation, and performance including wear resistance, with material selection being of critical importance. Compliant mechanisms have emerged as a strong candidate for replacement of multi-component mechanical assemblies with monolithic-type designs potentially overcoming many of these inherent challenges. For example, intrinsic flexures may replace multi-part hinges thereby eliminating assembly, lubrication and backlash, as well as potentially reducing overall manufacturing costs. The principal merits of Bulk Metallic Glasses (BMGs) have been well documented over the last 40 years, with a wide number of metallic glass families shown to exhibit high specific strength, elasticity, corrosion resistance, hardness, and wear resistance.This paper presents details of a current research project investigating implementation of BMG materials into compliant mechanisms for long-term space-based missions.
10:50 AM Invited
Nucleation of Shear Bands in Al-based Metallic Glasses and Their Composites: Wan Kim1; Guen Hee Yoo1; Eun Soo Park1; John Perepezko2; 1Seoul National University; 2University of Wisconsin-Madison
A shear band(SB) is a region of highly localized plastic flow that develops during loading in metallic glasses(MGs). The deformation by SB is a nucleation-controlled process, however the initiation of the process is unclear. In the present study, we carefully investigate SB nucleation by measuring the first pop-in events via nanoindentation test. The statistical analysis of shear avalanches in Al90-xNi10MMx (x=2, 4, 6) MGs and Al88Ni10MM2 MG composites with different sizes and fractions of alpha-Al nanocrystals reveal the structural effects on the stochastic SB nucleation behavior. As a result, we discovered that there is the bimodal distribution of the first pop-in loads that are associated with different SB nucleation sites by concentrated shear mechanism and diffuse shear transformation mechanism. The density of each site, the nucleation barriers, and the nucleation kinetics have been carefully determined. These results offer novel guideline how to tailor the ductility of glass-forming alloys.
11:10 AM Cancelled
Near-net Forming Complex Shaped Zr-based Bulk Metallic Glasses by High Pressure Die Casting: LeHua Liu1; 1South China University of Technology
In this work, we open an approach named the “entire process vacuum high pressure die casting” (EPV-HPDC), which delivers the ability to fill die with molten metal in milliseconds, and create solidification under high pressure. Based on this process, various Zr-based BMGs were prepared by using industrial grade raw material. The results indicate that the EPV-HPDC process is feasible to produce a glassy structure for most Zr-based BMGs, with a large size and high strength. In addition, it has been found that EPV-HPDC process allows complex industrial BMG parts, some of which are hard to be formed by any other metal processes, to be net shaped precisely. The BMG components prepared by the EVP-HPDC process possess the advantages of dimensional accuracy, efficiency, and cost compared with the ones formed by other methods. The EVP-HPDC process paves the way for the large-scale application of BMGs.