Metallic Glasses (MGs):

Metallic Glasses (amorphous metals) are an interesting class of materials due to desirable properties such as high elastic limits, thermoplastic formability, and lack of brittleness at low temperatures. Despite intense interest, the identifying new glass forming alloys remains challenging due to their complex, disordered atomic structure and a lack of understanding about how that structure evolves during cooling from the liquid state.

Conventionally, MG discovery has been based on empirical investigations in which individual compositions are cast in series and the glass forming ability (e.g. critical casting dimensions) are evaluated. The development of high-throughput experimental methods to screen alloy compositions for glass forming ability and other properties, as well as computational methods to predict glass formation a priori, would drastically accelerate the alloy development cycle.

High-throughput Experimental Design of BMGs:

The Laser Engineered Net Shaping (LENS) instrument in the Flores lab can be used to produce compositional libraries of metallic systems, enabling the production of hundreds of distinct alloy compositions within minutes. By controlling the heat input to the system (via laser power and travel speed), the relative glass forming ability of the alloys can be evaluated as well, permitting identification of the “best” glass former. The dimensions of the libraries also lend themselves to property characterization, for example using nanoindentation. The speed and efficiency of this method is a great improvement over traditional serial casting methodologies and has an advantage over vapor-deposition techniques due to the more realistic conditions provided by liquid vitrification.

High-temperature Molecular Dynamics prediction of glass forming ability in metallic alloys:

Molecular Dynamics (MD) simulations can be used to investigate high-temperature structural evolution of metallic alloys, which can then be used as a predictor of glass-forming ability (GFA). Our research suggests that the mathematical variance of the population of Voronoi clusters in the liquid is directly related to GFA in metallic alloys, where a lower variance corresponds to higher GFA. This suggests that alloying strategies that promote competition among atomic packing motifs in the liquid increase the barrier to crystal nucleation, thereby improving GFA.

Publications on Metallic Glasses

W.P. Weeks and K.M. Flores, Improving the precision of  Vickers indentation measurements in soda-lime glass with increased dwell time, J. Non-Crystalline Solids 605, 122174 (2023). DOI: 10.1016/j.jnoncrysol.2023.122174

W.P. Weeks and K.M. Flores, Using characteristic structural motifs in metallic liquids to predict glass forming ability, Intermetallics 145, 107560 (2022). DOI: 10.1016/j.intermet.2022.107560

J. Wang, A. Agrawal and K.M. Flores, Are hints about glass forming ability hidden in the liquid structure?, Acta Materialia 171, 163-169 (2019). DOI: 10.1016/j.actamat.2019.04.001

P. Tsai, K. Kranjc, and K.M. Flores, Hierarchical heterogeneity and an elastic microstructure observed in a metallic glass alloy, Acta Materialia 139 11-20 (2017). DOI: 10.1016/j.actamat.2017.07.061

P. Tsai and K.M. Flores, High-throughput discovery and characterization of multicomponent bulk metallic glass alloys, Acta Materialia 120 426-434 (2016). DOI: 10.1016/j.actamat.2016.08.068

A. Hunter, V. Araullo-Peters, M. Gibbons, O.D. Restrepo, S.R. Niezgoda, W. Windl, K.M Flores, D.C. Hofmann, and E.A. Marquis, Three-dimensional imaging of shear bands in bulk metallic glass composites, Journal of Microscopy 264 304-310 (2016). DOI: 10.1111/jmi.12443

J.A. Kolodziejska, H. Kozachkov, K. Kranjc, A. Hunter, E. Marquis, W.L. Johnson, K.M. Flores, and D.C. Hofmann, Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites, Scientific Reports 6 22563:1-8 (2016). DOI: 10.1038/srep22563.

G.R. Khanolkar, S. Haghighat, A.M. Hodge, K.M. Flores and V. Eliasson, Effect of loading rate on dynamic fracture morphology of a Zr-based bulk metallic glass, Materials Transactions 56(6), 840-843 (2015). DOI: 10.2320/matertrans.M2014467

A. Vivek, M. Presley, N.H. Hutchinson, K.M. Flores, and G.S. Daehn, Solid state impact welding of BMG and copper by vaporizing foil actuator welding, Materials Science and Engineering A 634, 14-19 (2015). DOI:10.1016/j.msea.2015.03.012

P. Tsai and K.M. Flores, A laser deposition strategy for the efficient identification of glass forming alloys, Metallurgical and Materials Transactions A 46A, 3876-3882 (2015). DOI: 10.1007/s11661-015-2900-x

P. He, L. Li, F. Wang, O. Dambon, F. Klocke, K.M.Flores, A.Y. Yi, Bulk metallic glass mold for high volume fabrication of micro optics, Microsystem Technologies, 1-7 (2014). DOI: 10.1007/s00542-014-2395-1

P. Tsai and K.M. Flores, A combinatorial strategy for metallic glass design via laser deposition, Intermetallics 55, 162-166 (2014). DOI:10.1016/j.intermet.2014.07.017

A. Agrawal, R. Mishra, L. Ward, K.M. Flores, and W. Windl, Embedded atom method potential of beryllium, Modelling and Simulation in Materials Science and Engineering 21, 085001 (2013). DOI:10.1088/0965-0393/23/6/069501

L. Ward, D. Miracle, W. Windl, O.N. Senkov, and K.M. Flores, Structural evolution and kinetics in Cu-Zr metallic liquids from molecular dynamics simulations, Physical Review B 88, 134205 (2013). DOI:10.1103/PhysRevB.88.134205

H. Sun and K.M. Flores, Spherulitic crystallization mechanism of a Zr-based bulk metallic glass via laser processing, Intermetallics 43, 53-59 (2013). DOI:10.1016/j.intermet.2013.06.010

R.L. Narayan, P.S. Singh, D.C. Hofmann, N. Hutchinson, K.M. Flores, and U. Ramamurty, On the microstructure – tensile property correlations in bulk metallic glass matrix composites with crystalline dendrites, Acta Materialia 60, 5089 (2012). DOI:10.1016/j.actamat.2012.06.032

A. Bharathula and K.M. Flores, Variability in yield strength of a metallic glass at micron and sub-micron length scales, Acta Materialia 59, 7199 (2011). DOI:10.1016/j.actamat.2011.08.008

H. Sun and K.M. Flores, Spherulitic crystallization behavior of a metallic glass at high heating rates, Intermetallics 19, 1538 (2011). DOI:10.1016/j.intermet.2011.05.022

A. Bharathula, S.-W. Lee, W.J. Wright, and K.M. Flores, Compression testing of metallic glass at small length scales: Effects on deformation mode and stability, Acta Materialia 50, 5789 (2010). DOI: 10.1016/j.actamat.2010.06.054

H. Sun and K.M. Flores, Microstructural Analysis of a Laser-Processed Zr-Based Bulk Metallic Glass, Metallurgical and Materials Transactions A 41A, 1752 (2010). DOI: 10.1007/s11661-009-0151-4

H. Sun and K.M. Flores, Laser deposition of a Cu-based metallic glass powder on a Zr-based glass substrate, J. Materials Research 23, 2692 (2008). DOI:10.1557/JMR.2008.0329

A. Bharathula, W. Luo, W. Windl, and K.M. Flores, Characterization of open volume regions in a simulated Cu-Zr metallic glass, Metallurgial and Materials Trans. A 39A, 1779 (2008). DOI: 10.1007/s11661-008-9503-8

D. B. Miracle, T. Egami, K. Kelton, and K. M. Flores, Structural aspects of metallic glasses, MRS Bulletin 32, 629 (2007). DOI: 10.1557/mrs2007.124

K. M. Flores, E. Sherer, A. Bharathula, H. Chen, Y.C. Jean, Sub-nanometer Open Volume Regions in a Bulk Metallic Glass Investigated by Positron Annihilation, Acta Materialia 55, 3403 (2007). DOI: 10.1016/j.actamat.2007.01.040

K. M. Flores, B. P. Kanungo, S. C. Glade, and A. Asoka-Kumar, Characterization of plasticity-induced structural changes in a Zr-based bulk metallic glass using positron annihilation spectroscopy, J. Non-Crystalline Solids 353, 1201 (2007). DOI:10.1016/j.jnoncrysol.2006.11.017

K. M. Flores and R. H. Dauskardt, Mode II Fracture Behavior of a Zr-Based Bulk Metallic Glass, J. Mechanics and Physics of Solids 54, 2418 (2006). DOI: 10.1016/j.jmps.2006.05.003

K. M. Flores, Structural Changes and Stress State Effects During Inhomogeneous Flow of Metallic Glasses, Scripta Materialia 54, 327 (2006). DOI:10.1016/j.scriptamat.2005.04.049

B.P. Kanungo, S.C. Glade, P. Asoka-Kumar, and K.M. Flores, Characterization of Free Volume Changes Associated with Shear Band Formation in Zr- and Cu-Based Bulk Metallic Glasses, Intermetallics 12, 1073 (2004). DOI:10.1016/j.intermet.2004.04.033

K. M. Flores and R. H. Dauskardt, Fracture and Deformation of Bulk Metallic Glasses and their Composites, Intermetallics 12, 1025 (2004). DOI:10.1016/j.intermet.2004.05.004

K. M. Flores, W. L. Johnson, and R. H. Dauskardt, Fracture and Fatigue Behavior of a Zr-Ti-Nb Ductile Phase Reinforced Bulk Metallic Glass Matrix Composite, Scripta Materialia 49, 1181 (2003). DOI:10.1016/j.scriptamat.2003.08.020

K. M. Flores, D. Suh, R. H. Dauskardt, P. Asoka-Kumar, P. Sterne, and R. Howell, Characterization of Free Volume in a Bulk Metallic Glass Using Positron Annihilation Spectroscopy, J. Materials Research 17, 1153 (2002). DOI:10.1557/JMR.2002.0171

P. Asoka-Kumar, R. Howell, T. G. Nieh, P. A. Sterne, B. D. Wirth, R. H. Dauskardt, K. M. Flores, D. Suh, G. R. Odette, Opportunities for materials characterization using high-energy positron beams, Applied Surface Science 194, 160 (2002).  DOI:10.1016/S0169-4332(02)00118-6

K. M. Flores and R. H. Dauskardt, Mean Stress Effects on Flow Localization and Failure in a Bulk Metallic Glass, Acta Materialia 49, 2527 (2001). DOI:10.1016/S1359-6454(01)00125-2

K. M. Flores, D. Suh, R. Howell, P. Asoka-Kumar, P. Sterne, and R. H. Dauskardt, Flow and Fracture of Bulk Metallic Glass Alloys and their Composites, Materials Transactions JIM 42, 619 (2001). DOI: 10.2320/matertrans.42.619

K. M. Flores and R. H. Dauskardt, Crack Tip Plasticity in Bulk Metallic Glasses, Materials Science and Engineering A A319-321, 511 (2001). DOI:10.1016/S0921-5093(01)01111-X

K. M. Flores and R. H. Dauskardt, Enhanced Toughness Due to Stable Crack Tip Damage Zones in Bulk Metallic Glass, Scripta Materialia 41, 937 (1999). DOI:10.1016/S1359-6462(99)00243-2

K. M. Flores and R. H. Dauskardt, Local Heating Associated with Crack Tip Plasticity in Zr-Ti-Ni-Cu-Be Bulk Amorphous Metals, J. Materials Research 14, 638 (1999). DOI: 10.1557/JMR.1999.0642