Bulk Metallic Glasses XVII: Poster Session
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

Tuesday 5:30 PM
February 25, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr


J-9: Atomic Structure and Properties of Co-Ta-B Bulk Metallic Glasses: Ivan Kaban1; Pál Jóvári2; Ju Wang1; Mark Adam Webb3; Ning Chen3; Jacques Darpentigny4; 1IFW Dresden, Germany; 2Wigner Research Centre for Physics, Budapest, Hungary; 3Canadian Light Source, Saskatoon, Canada; 4Laboratoire Léon Brillouin, CEA-Saclay, France
    This contribution reports a study of the ternary Co-Ta-B bulk metallic glasses with a constant boron content of 33 at.% and a variable Co-Ta ratio. Glassy rods with a diameter up to 2.5 mm exhibit ultimate compressive strength between 5.4 and 6.2 GPa and plastic strain between 0.5 and 3.2%, making them very attractive for some applications. The glass-forming ability and mechanical properties of the studied glasses are discussed in relationship to the alloy composition, atomic structure and interatomic bonding. The structural studies of Co-Ta-B glass have been carried out using different diffraction techniques and X-ray absorption spectroscopy as well as reverse Monte-Carlo simulation.

J-10: Competitive Formation of Metallic Glasses in Ternary Eutectic Systems: Dong Ma1; 1Oak Ridge National Laboratory
    The competitive growth principle that governs phase selection during solidification has been utilized to investigate the formation of metallic glasses in binary and ternary eutectic systems. The model indicates that the glass formation is due to the suppression of all primary competing crystalline phases and eutectic structures. A new criterion gauging the globally optimum glass-forming ability in eutectic systems is derived, with a corollary that the best glass-forming composition zone can be either symmetric, or asymmetric, about the eutectic composition. The practical implementation and significance of the strategies is demonstrated by discovering bulk metallic glasses in Zr-based eutectic systems.

Cancelled
J-11: Effect of Ce Additive on Magnetic Properties and Glass Forming Ability of Fe-Si-B-P Amorphous Alloys: Youngsin Choi1; Sun-Yeoung Ki1; Joo Hyun Park2; Hwi-Jun Kim1; 1Korea Institute of Industrial Technology / Liquid Processing & Casting R&D Group; 2Department of Materials Science and Chemical Engineering, Hanyang University
    Due to the characterization of low coercivity and high permeability, soft magnetic amorphous alloys have been used in various industrial fields such as high frequency inductor core, transformer core and electromagnetic wave shielding sheets. Amorphous structure of Fe-based soft magnetic alloys has been enhanced by adding alloy elements with larger atomic radius compared to matrix Fe. In this study, we investigated the effect of Ce additive on magnetic properties and glass forming ability of Fe81-xSi3B6P10Cex (x=0, 0.5, 1.0, 1.5, 2.0) alloys. Phase analysis of Fe-based amorphous ribbons was performed by DSC and XRD after melt spinning process. Glass forming ability of these alloys was measured by both microstructure and DSC after suction casting. Furthermore, the relationship between Ce contents and soft magnetic properties such as saturation magnetization (Ms) and coercivity (Hc) was estimated through vibrating sample magnetometer analysis.

J-12: High Saturation Magnetic Flux Density of New Nanocomposite Materials Annealed in Various Temperatures: Seoyeon Kwon1; Haein Choi-Yim1; 1Sookmyung Women's University
    Some characteristics of amorphous nanocomposites that differentiate them from other soft magnetic materials include high saturation magnetic flux density (Bs), low magnetic loss, and high permeability (μ). Moreover, a wide range of B-H properties can be acquired through heat-treatment of the alloys in different conditions. In the present study, the magnetic and microstructural properties were investigated of nanocrystalline soft magnetic alloy with the composition of Fe80Si7B9Nb3Cu1 fabricated by the melt-spinning method. The longitudinal magnetic field annealing contributed to the uniform distribution of α-Fe nanocrystals. The lowest core loss (Pcv) was 124.0 mW/cm3 annealed at 560 ℃. Furthermore, the core annealed at 560 ℃ showed the enhancement in Bs with the value of 1.57 T as compared to the conventional value of FINEMET core (Bs = 1.23 T). The combination of high Bs with excellent magnetic properties makes this nanocomposite alloy an outstanding economical application in the high frequency (f) region.

J-13: Shear Transformation Zone Properties from Nonlinear Anelastic Deformation: Tianjiao Lei1; Michael Atzmon1; 1University of Michigan
    Anelastic deformation of metallic glasses (MGs) is an ideal regime to study properties of shear transformation zones (STZs), which are atomic clusters responsible for shear transformation, since they are isolated and do not interact with each other. At high stress, when the viscosity is non-Newtonian, the details of the activation volume can be obtained, which are unavailable in the linear regime. We have developed a constraining method with bending strain up to ~ 1.55% for Al86.8Ni3.7Y9.5 MG. The anelastic strain is highly nonlinear in the stress, which is mainly due to the non-equilibrated largest and slowest active STZs at the end of constraining period. Using nonlinear kinetics under constraint and zero bending moment after constraint removal, the volume of the largest active STZs and the transformation shear strain are obtained independently for the inherent state: 4.8ˇ10^-28 m^3 and 0.18, respectively.

J-14: The Effect of Severe Plastic Deformation on the Relaxation Dynamics of a Bulk Metallic Glass Studied by X-ray Photon Correlation Spectroscopy: Hongbo Zhou1; Gerhard Wilde1; 1University of Muenster
    The relaxation dynamics of the Pd40Ni40P20 (at.%) metallic glass severely deformed by high-pressure torsion was investigated by high-resolution X-ray photon correlation spectroscopy on the atomic length scale at a series of temperatures upon heating. We found that the relaxation dynamics of the deformed sample gets accelerated compared with the undeformed sample. This indicates that rejuvenation has occurred.At temperatures below 423 K, the activation energies of both undeformed and deformed samples are approximately 21.2 kJ/mol. This indicates that the relaxation process at the low temperature is stress-dominated and the deformation could only improve the atomic mobility without changing the energy barrier. From 473 K to 533 K, a “crossover” behavior of the effective relaxation time occurs, which is due to a transition of the relaxation mechanism from a stress-dominated to a diffusion-dominated process. Upon further increase in temperature, the relaxation is accelerated dramatically and entering the glass transition process.