Bulk Metallic Glasses XIV: Mechanical and Other Properties I
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Peter Liaw, University of Tennessee; Hahn Choo, University of Tennessee; Yanfei Gao, University of Tennessee; Yunfeng Shi, Rensselaer Polytechnic Institute; Xie Xie, The University of Tennessee; Gongyao Wang, The University of Tennessee; Jianzhong Jiang, Zhejiang University

Thursday 8:30 AM
March 2, 2017
Room: 33B
Location: San Diego Convention Ctr

Session Chair: Koichi Tsuchiya, NIMS; Upadrasta Ramamurty, Indian Institute of Science

8:30 AM  Invited
Thermal and Mechanical Properties of Deformation-Induced Amorphous Phase in Zr-Cu-Al Alloys: Koichi Tsuchiya1; Jian Qiang2; Fanqiang Meng3; 1NIMS; 2NIMS; University of Tsukuba; 3Ames Laboratory, University of Iowa
    While amorphous alloys are usually fabricated by fast cooling the melt, alternative path can be through solid-state amorphization by severe plastic deformation. Since the mechanisms of the amorphous formation during fast-cooling and severe plastic deformation are quite different, the difference in the structures and various properties of the resulting amorphous alloys is worth investigating. In the present study, severe plastic deformation by high-pressure torsion (HPT) was utilized to induce amorphization starting from crystalline Zr-Cu-Al alloys. The thermal properties and mechanical property of the resulting sample will be compared to that of the amorphous counterpart produced by rapid solidification.

8:50 AM  Invited
Crystallization Behavior and Soft Magnetic Properties of (Fe36Co36B19.2Si4.8Nb4)99.5Cu0.5 Bulk Metallic Glass: Mihai Stoica1; Parthiban R.1; Ivan Kaban1; Sergio Scudino1; Jürgen Eckert2; 1IFW Dresden, Germany; 2ESI Leoben, Austria
    Using the induction melting combined with injection copper mold casting, fully amorphous (Fe36Co36B19.2Si4.8Nb4)99.5Cu0.5 rods with diameters up to 2 mm and a length of 5 cm were successfully cast. If the base composition forms by primary crystallization Fe23B6-type phase, the addition of Cu drastically change the thermal behavior. Upon heating the new glassy alloys gradually forms (Fe,Co) solid solution. Further, the dimension and the volume fraction of the bcc crystals control the soft magnetic properties. The precipitation of bcc (Fe,Co) takes place within a temperature interval of 100 K, with high nucleation rate at the initial stage. The present work aimed to explore the mechanism of phase formation upon heating by means of time-resolved X-Ray diffraction in transmission configuration using synchrotron radiation. Based on these results, new annealing treatments were defined and the resulted structures and soft magnetic properties in details analyzed.

9:10 AM  Student
Structural Rejuvenation in Bulk Metallic Glasses with Varying Fictive Temperature: Hui Wang1; Wojciech Dmowski1; Jittisa Ketkaew2; Jan Schroers2; Zengquan Wang1; Takeshi Egami1; 1University of Tennessee, Knoxville; 2Yale University
    The thermal history of the BMGs was found to be important factor that influences the plasticity of the BMGs. The fictive temperature, Tf, was proposed to characterize the disordered structure of the BMGs inherited from liquids. The dependence of mechanical properties on Tf were reported. For instance, Ketkaew et al. (unpublished) measured the fracture toughness of Zr44Ti11Cu10Ni10Be25 BMGs with different Tf. In this work, the structures of Zr44Ti11Cu10Ni10Be25 BMGs with different Tf were studied through high-energy x-ray diffraction under deformation in the elastic regime. From PDF analysis, we observed that the structure tends to be more disordered with the increasing Tf. Furthermore, we examined the local non-affine deformation and found that the density of the local topological rearrangements (LTRs) increases with Tf, which correlates with plasticity. This result of the microscopic structure well explained the trend of its macroscopic fracture toughness. Work supported by the U.S. DOE, DE-AC05-00OR-22725.

9:30 AM  
Controllable Thermal Stress and Micro-cracking in Processing Metallic Glasses by Selective Laser Melting: Ning Li1; Di Ouyang1; Jianji Zhang1; Lin Liu; 1Huazhong University of Science and Technology
    The ability to understand, predict and control thermal stress is crucial to selective laser melting of metallic glasses. Here, the origin of the thermal stress is probed through theoretical analysis, experiments and finite element simulation. The results revealed that the high thermal stresses caused mainly by the temperature gradient during rapid solidification, facilitates the initation of micro-cracks in three dimensional spaces. A 3D printing map that illustrates the correlation between fracture toughness and micro-crack is constructed, providing theoretical predication for choosing alloy systems lack of crack during SLM. The present results not only offer better in-depth understanding of the physical origin of micro-cracks, but also provide promising methods to moderate stress field near the crack tip and shield the initiation of crack propagation in the 3D printing of bulk metallic glasses.

9:50 AM  Invited
On the Fracture Toughness and Fatigue Strength of Ni-based Glasses: Bernd Gludovatz1; Edwin Chang1; Mingxi Zheng1; Jong Na2; Maximilien Launey2; Marios Demetriou3; William Johnson3; Robert Ritchie1; 1Lawrence Berkeley National Laboratory; 2Glassimetal Technology Inc; 3Caltech
    The excellent combination of properties like high strength, low stiffness, and large elastic strain limits make bulk-metallic glasses (BMGs) candidate materials for many structural applications. One of the main drawbacks for their use in engineering fields are the often limited dimensions of casts of plates and rods and their somewhat expensive production costs. In terms of damage tolerance, BMGs now show reasonably high fatigue limits whereas strength and toughness behave generally mutually exclusive with fracture toughness values often unacceptably low (<10 MPa.m^1/2) when strength levels exceed 2 GPa. Here, we report on a cost-effective Ni-based BMG of 2.5 GPa strength that can be processed with a centimeter-thick cross section and shows a plane strain fracture toughness of ~27 MPa.m^1/2. We compare the glass’ fatigue endurance limit in both air and 0.5M NaCl corrosive environment to another Ni-glass with higher Cr-content and other BMGs like Vit105.

10:10 AM Break

10:30 AM  Student
Bulk Metallic Glasses Composites Produced via Severe Plastic Deformation – Microstructure and Mechanical Properties: Lisa Kraemer1; Verena Maier-Kiener2; Karoline Kormout1; Yannick Champion3; Reinhard Pippan1; 1Erich Schmid-Institute of Materials Sciences, Austrian Academy of Sciences; 2Department Physicial Metallurgy and Materials Testing; 3Grenoble INP
    Bulk metallic glasses (BMGs) can be produced via different routes. One innovative way to fabricate not only BMGs, but also BMG composites is High Pressure Torsion (HPT). With it, it is possible to start with powders and to easily control the applied strain and so the microstructure. Composites with two amorphous phases (Zr-based and Ni-based) and an amorphous and a crystalline phase (Cu) were produced. The obtained microstructures of the composites were studied and correlated to the mechanical properties by using different methods such as nanoindentation and in-situ SEM micropillar compression. The deformation behavior was characterized under ambient but also non-ambient conditions. Deformation behavior and mechanical properties change due to the second phase. A change in hardness, Young’s Modulus, fracture strength and fracture strain can be observed. Additionally, XRD, TEM and SEM investigations help to understand the structural evolution as a function of the applied strain during the HPT-process.

10:50 AM  
The Origins of Excellent Soft Magnetism in Fe65.5Cr4Mo4Ga4P12B5.5C5 Bulk Metallic Glasses: T. D. Shen1; B. R. Sun1; S. W. Xin1; 1Yanshan University
    We have made Fe65.5Cr4Mo4Ga4P12B5.5C5 bulk metallic glasses (BMGs) by a flux-meting and water-quenching technique and studied their magnetic structure-property relations. The coercivity and permeability of our Fe-based BMGs are comparable to those of annealed zero-magnetostriction cobalt-based glassy ribbons. The total power loss of our thick Fe-based BMGs is similar to or even lower than that of thin glassy Fe-based ribbons. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) observations suggest that the low coercivity of our BMGs can be explained by their low residual stress, low content of non-magnetic inclusions, and low ratio of surface roughness to specimen thickness. The unexpected low total power loss achieved in our thick BMGs is mainly because their excess eddy current loss is negligible. In contrast, the excess eddy current loss is often at least one to two orders of magnitude greater than the classical eddy current loss in thin glassy ribbons.

11:10 AM  
Rapid Degradation of Azo Dye by Co-Si-B Metallic Glass Powder: XinDong Qin1; ZhengKun Li1; ZhengWang Zhu1; HuaMeng Fu1; Hong Li1; AiMin Wang1; HongWei Zhang1; HaiFeng Zhang1; 1Insitute of Metal Research, Chinese Academy of Sciences
    The outstanding performance of ball-milled Co-based metallic glass powder in degrading dye wastewater is reported. Higher activity and lower mass loss of the Co-based metallic glass solve the insurmountable problems in conventional zero-valent metal technology to treat environmental contaminants. Acid orange II in aqueous solution was completely degraded in two minutes by the Co-based metallic glass powder, which is much faster than the treatment by the widely studied zero-valent iron powder. The coordinatively unsaturated local structure of the metallic glass responds to the catalysis for degradation, resulting in very low mass loss. The Co-based metallic is the most efficient material for azo dye degradation reported thus far, and will promote the practical application of metallic glass as functional material.

11:30 AM  Cancelled
Crack Propagation of Metallic Glasses: Gang Wang1; J. Li1; J. Yi1; I. Hussain1; W. Y. Wang1; 1Shanghai University
    The failure mode of metallic glass can be dominated by shear-banding failure (for tough MGs) or cracking failure (for brittle MGs). During the fracture process, crack formation and propagation create a nonlinear strain field at crack tip. The transportation of the strain energy stored in the strained MG to the crack tip is of importance in understanding the deformation mechanism of MGs. By using digital image correlation method, we perform direct and precise measurements of the strain concentration in four MGs. After yielding, plastic deformation is localized into shear bands or crack tip, which means a systematic transition from the linear elastic behavior to the strongly nonlinear behavior. The failure modes are discussed based on a hyperelasticity model. This result provides a comprehensive picture of how remotely applied forces drive MGs failure in the fundamentals of fracture states.