Bulk Metallic Glasses XX: Physical and Mechanical Properties I
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Robert Maass, Federal Institute of Materials Research and Testing (BAM); Peter Derlet, Paul Scherrer Institut; Katharine Flores, Washington University in St. Louis; Yonghao Sun, The Chinese Academy of Sciences; Lindsay Greer, University of Cambridge; Peter Liaw, University of Tennessee
Wednesday 2:00 PM
March 22, 2023
Room: Aqua C
Location: Hilton
Session Chair: Robert Maass, Federal Institute of Materials Research and Testing (BAM)
2:00 PM
Structural Development of (Fe36Co36B19.2Si4.8Nb4)99.5Cu0.5 BMG: Mihai Stoica1; Noemi Cerboni2; Alexander Firlus1; Stephan Gerstl1; Robin Schäublin1; Jörg Löffler1; 1ETH Zurich; 2Paul Scherrer Institute
Fe-based nanocrystalline alloys are materials with excellent soft-magnetic properties, showing very low coercivity, high permeability and a magnetic saturation of 1.2-1.3 T. These properties originate from their particular structure, which in the case of e.g. Finemet or Vitroperm consists of bcc (Fe,Si) nanograins embedded in a remnant amorphous matrix. However, these alloys can be obtained in nanocrystalline form only by annealing the amorphous precursor, i.e. the metallic glass (MG) ribbon. Recently, we demonstrated the possibility of casting similar alloys in bulk form and elucidated the crystallization mechanism by time-resolved X-ray diffraction studies. Here we show the possibility to control the resulting macroscopic magnetic properties by tailoring the structure upon thermal annealing. In contrast to the known MG ribbons, our bulk samples build by primary crystallization distorted bcc (Fe,Co) nanocrystals, with the Cu clusters not necessarily acting as centers for the nanocrystallization.
2:20 PM
Property Studies on Atomically Smooth Metallic Glasses: Amit Datye1; Zheng Chen1; Chao Zhou1; Xinzhe Wang1; Shuhan Zhang1; Jittisa Ketkaew1; Sungwoo Sohn1; Omur E. Dagdeviren2; Jan Schroers1; Udo Schwarz1; 1Yale University; 2University of Quebec
In recent years, nanoimprinting of bulk metallic glasses (BMGs) by thermoplastic forming has enabled the manufacturing of samples made from Pt57.5Cu14.7Ni5.3P22.5 BMG featuring atomically smooth terraces using SrTiO3 single crystals as molds. Due to their sub-angstrom RMS surface roughness, these atomically smooth samples are ideally suited to be used in high-resolution investigations of BMG properties by surface-sensitive methods such as atomic force microscopy. Here, we present results from a variety of studies: (1) How BMGs can be used to replicate sub-angstrom features of any size; (2) how such structures can be accurately maintained despite almost complete crystallization; (3) how annealing-induced relaxation and crystallization affects surface morphology is studied, revealing that the surface rearranges and relaxes towards a more stable, denser packed glass; (4) how stiffness mapping can be used to study preparation-dependent inhomogeneities in the glass and (5) how preparation parameters affect atomic-scale plastic flow.
2:40 PM
Atomic-scale Nature of the Invar Effect in Fe-based Bulk Metallic Glasses: Alexander Firlus1; Mihai Stoica1; Stefan Michalik2; Gavin Vaughan3; Robin Schäublin1; Jörg Löffler1; 1ETH Zurich; 2Diamond Light Source; 3European Synchrotron Radiation Facility (ESRF)
Fe-based bulk metallic glasses (BMGs) universally show an anomalously low coefficient of thermal expansion below their Curie temperature. This effect is known as Invar effect. It is well known at the macroscopic scale but its atomic origins are little understood. There is agreement that it is a magnetic effect, but the role of the atomic species and the impact of the disordered atomic arrangement on the universality of the Invar effect is unknown.In this work we studied the thermal expansion at the atomic scale by in-situ X-ray diffraction on multiple quaternary BMGs. All these BMGs show a reduced thermal expansion of the interatomic distances below the Curie temperature. Through variation of the minor alloying elements the origin of the Invar effect can be attributed to the disordered Fe network. Together with atomic-scale dilatometry measurements on multiple BMGs, we present our improved understanding of the Invar effect in amorphous materials.
3:00 PM Invited
Construction of Three-dimensional Deformation Sequence Map in Bulk Metallic Glasses: Wook Ha Ryu1; Won-Seok Ko2; Haruka Isano3; Rui Yamada3; Heh Sang Ahn1; Geun Hee Yoo1; Kook Noh Yoon1; Junji Saida3; Eun Soo Park1; 1Seoul National University; 2Inha University; 3Tohoku University
Herein, we systematically investigate the compressive plasticity and shear band (SB) behavior of the Zr-based bulk metallic glasses (BMG) with various combinations of Poisson’s ratio, aspect ratio, and contact friction. First, we propose three stages of plastic flow through quantitative analysis of serrated flow: (stage I) apparent hardening region with the stochastic serrated flow, (stage II) constant yielding region with the steady-state serrated flow, (stage III) macroscopic softening region with the confined serrated flow. Secondly, we construct a three-dimensional deformation sequence map that reflects the key variables for SB behavior, and the map can explain how to stabilize stage II (or destabilize stage III) by simultaneously considering the influence of the variables. We carefully discuss how to design BMG to be deformable like ductile crystalline alloys. Our study paves the way for the development of sustainable BMGs with a predictable deformation behavior by tailoring the key variables for SB behavior.
3:20 PM Break
3:40 PM Invited
Effect of Impurities on the Mechanical Properties of Commercial-grade Bulk Metallic Glass: Douglas Hofmann1; Punnathat Bordeenikasem1; Thomas Freeman1; Melanie Buziak1; 1NASA Jet Propulsion Laboratory
Transitioning bulk metallic glass (BMG) research into real-world applications requires the use of commercial manufacturing equipment to produce feedstock materials. Large-scale production can introduce impurities (such as oxygen, carbon, iron, tin, etc.) into the melt and create compositions of BMGs that are off-nominal in composition. Understanding the sensitivity in the glass forming ability and mechanical properties across different BMG compositions is critical towards their infusion into applications like gears, flexures, mechanisms, robotics, actuators, brackets, and inserts. In this work, we look at three BMG alloys of commercial interest; a titanium-zirconium BMG with excellent glass forming ability, a titanium-based BMG with low density, and a copper-zirconium BMG with excellent wear resistance. Each alloy was made commercially with varying degrees of impurities introduced during manufacturing and the properties were compared with laboratory-grade material and with mixtures of the commercial alloy with other, strategic alloys. Control over the resulting properties is demonstrated.
4:00 PM
Nano-mechanical Probing of Elasticity Length Scales in Metallic Glasses: Birte Riechers1; Robert Maaß2; 1Federal Institute of Materials Research And Testing (BAM); 2Federal Institute of Materials Research and Testing (BAM), University of Illinois at Urbana-Champaign
Metallic glasses have a disordered atomic structure beyond some short- or medium-range order. While the first is associated with nearest neighbor atoms, the latter occurs due to the atoms’ tendency to form clusters of interconnected icosahedral structures as demonstrated in atomistic simulations, giving direct insight into emerging structural length scales (JALCOM 821, 153209, 2020). As discussed in our earlier work (Adv. Func. Mat. 28, 1800388, 2018), measuring structural heterogeneities bears the potential of formulating structure-property relationships for metallic glasses, reminiscent of those that enabled the success of crystalline alloys. But which probing length scale is suitable to experimentally assess the structural state of glassy metals? Here we discuss recent advances made by nano-mechanical testing to spatially resolve property fluctuations in metallic glasses from the nanometer to micrometer scale and demonstrate material-specific and instrument-related challenges along our own and the community’s path to experimentally quantify structural length scales of glassy metals.
4:20 PM
On the Correlation between Multiscale Structural Heterogeneities and Mechanical Properties in Metallic Glasses: Dong Han1; Yunjiang Wang2; Yanfei Gao1; 1University of Tennessee; 2Institute of Mechanics, Chinese Academy of Sciences; University of Chinese Academy of Sciences
Atomic and microscopic heterogeneities play a critical role in governing the physical and mechanical properties of metallic glasses. A general theoretical protocol is proposed to describe the link via a statistical parameter quantifying the dynamic heterogeneity of glass-forming systems. The parameter can be calculated using the concept associated with the variation in the activation barriers to local structural excitations on the underlying potential energy landscape, which can be explored extensively using the recently developed activation-relaxation technique in inherent structures spanning a wide range of configurational space. During the process, the relationships between the multiscale heterogeneities and macroscopic plasticity are clearly captured. With increasing structural relaxation, the diversity of structural energy states drops by a large amount of magnitude. The mechanical behavior is a consequence of the convolution of the intrinsic thermal activation process and such heterogeneities.
4:40 PM
Achieving High Strength and Toughness by Modulating Metallic Glass Composition at the Nanoscale: Ali Behboud1; Amir Motallebzadeh2; Sezer Ozerinc1; 1Middle East Technical University; 2Koç University Surface Science and Technology Center (KUYTAM)
We report on the effect of compositional heterogeneities on the mechanical behavior of amorphous nanocomposites. The study aims to directly engineer such heterogeneities and gain insight into the resulting ductility improvements recently reported in the literature. The work considered magnetron sputtered ZrTa, which showed a fully amorphous structure over a wide compositional range of 35 – 70at.% Zr. Based on this data, we produced Zr35Ta65/Zr70Ta30 nanolayers with layer thicknesses in the range of 10 – 100 nm. The composite’s hardness was virtually the same as the harder constituent, Zr35Ta65, around 8.5 GPa. The nanolayered structure’s fracture toughness of 4.5 MPa.m^1/2, on the other hand, exceeded those of the constituents in monolithic form. In conclusion, the nanoheterogeneous structure improves the fracture toughness without sacrificing the hardness, providing a promising route for the design of new generation alloys overcoming the strength-ductility trade-off.