Bulk Metallic Glasses XIX: On-Demand Poster Session
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, Chinese Academy of Sciences; Lindsay Greer, University of Cambridge; Peter Liaw, University of Tennessee

Monday 8:00 AM
March 14, 2022
Room: Advanced Materials
Location: On-Demand Poster Hall


Amorphization of Si in Al-Cu-Si Ternary Alloy System with Liquid Quenching Process: Rui Yamada1; Junpei T. Okada2; Takeshi Wada2; Haruka Isano3; Tomohiro Yoshikawa3; Junji Saida1; 1Frontier Research Institute for Interdisciplinary Sciences, Tohoku University; 2Institute for Materials Research, Tohoku University; 3Graduate School of Engineering, Tohoku University
    Nowadays, liquid quenching process is widely used for fabricating amorphous materials. Recently, unprecedented method was proposed in our collaborative research group (IMR, Tohoku University). They intendedly selected the constituent elements with large difference of crystalline growth rates. It is supposed that the element with high growth rate easily crystallizes while for the element with slow growth rate remains in the liquid. During the quenching, the latter is expected to transform into the amorphous solid. By etching the crystalline phases, the amorphous material could obtain solely. In the latest study, they confirmed that the amorphous Si was obtained from the Al(non-facet)-Si(facet) eutectic system. In the present study, we extended it to the ternary alloy system by adding Cu with the aim of improving the whole glass forming ability. The microstructure evolutions in different conditions (alloy compositions, cooling rates) and the mechanism of the amorphization of Si are discussed.

Bulk Intrinsic Heterogeneity of Metallic Glasses Probed by Meissner Effect : Shubin Li1; Fujun Lan2; Qian Dong2; Qiaoshi Zeng1; 1Center for High Pressure Science & Technology Advanced Research; 2Shanghai Jiao Tong University
     Structural heterogeneity has been proposed as a key intrinsic feature of metallic glasses; however, It is still challenging in characterizing the atomic-scale heterogeneity in metallic glasses. In this work, we employed the Meissner effect of superconductivity in magnetic susceptibility measurements as a sensitive bulk probe and successfully revealed the three-dimensional structural heterogeneity and its two-way evolution tuned by structural aging or rejuvenation in a La-based metallic glass. Compared with the resistivity measurements which only signal the most superconductive loop in inhomogeneous materials, the diamagnetic susceptibility signal of the Meissner effect maps the volumetric distribution of all superconductive regions and the corresponding structural heterogeneity in metallic glasses. The experimental results reported in this work can be well interpreted based on a structural model of tunable “soft liquid-like” regions with soft vibration modes mixed with “hard solid-like” regions, validating the heterogeneity models of metallic glasses with new experimental data and approach.

Compression Experiments on Metallic Glass Specimens of Varying Size Differentiate between Models of Plasticity: Alan Long1; Wendelin Wright2; Xiaojun Gu2; Karin Dahmen1; 1University of Illinois; 2Bucknell University
    We compute scaling properties of stress-strain curves and associated serrations in different system sizes and compare the results with high-resolution compression experiments on bulk metallic glasses. The results show that it is possible to use the experiments to either confirm or rule out different models of plasticity.

Evolutionary Design of Machine-learning Predicted Bulk Metallic Glasses: Robert Forrest1; A. Greer1; 1University of Cambridge
     Glass-forming ability (GFA) remains a little-understood property. Experimental work on bulk metallic glasses (BMGs) is guided by many empirical criteria, often not of significant predictive value. This work aims to utilise machine-learning techniques both to produce predictive models for the GFA of alloy compositions, and to reveal insights useful for furthering our theoretical understanding of GFA. The produced machine-learning models simultaneously predict the liquidus temperature, glass transition temperature, crystallisation temperature, critical casting diameter, and probability of forming a BMG, for any given alloy.The incomprehensible size of composition space means even coarse grid-based searches for interesting alloys are infeasible unless constrained, requiring prior knowledge. Genetic algorithms provide a practical alternative, by rapidly homing in on fruitful regions and discarding others. Competition, recombination, and mutation are applied to a gene pool of alloy compositions, with the goal of evolving towards excellent BMG candidates as predicted by the machine-learning models.

Microstructures and Mechanical Properties of Non-toxic TiZr-based BMG Foams with Customized Porosity for Bio-implant Application: Po-Sung Chen1; Yu-Chin Liao1; Sin-Mao Song1; Pei-Hua Tsai1; Jason S. C. Jang1; Xavier Pei-Chun Wong2; Van Tai Nguyen3; 1National Central University; 2Taipei Medical University; 3Can Tho University
    Non-toxic TiZr-based bulk metallic glass foams (BMGFs) with customized porosity were successfully fabricated by hot pressing the mixture of TiZr-based metallic glass powder with different volume fraction of Al or Cu space holders at its supercooled temperature region under vacuum atmosphere. The XRD results reveal that the porous samples maintained amorphous states after hot pressing process. The corresponding porosities of each BMGFs were examined by SEM. Similar mechanical properties to the human bones can be obtained by tuning the porosity of the samples based on the Gibson and Ashby model. Increasing porosity of the samples led to a decrease of compressive strength and Young’s modulus. In the biocompatibility test, the fabricated porous sample by using Cu spacer particles show that cell viability increased with increasing incubation time. The results of calcium deposition rate are always higher than 100% and evidence that these BMGFs are positively biocompatible in the human body.